We're changing our WunderBlogs. Learn more about this important update on our FAQ page.

Change in the Weather: Climate Change and Arctic Oscillation (7)

By: Dr. Ricky Rood , 5:14 AM GMT on November 19, 2013

Change in the Weather: Climate Change and Arctic Oscillation (7)

This is the end-for-a-while of my series on the Arctic Oscillation / North Atlantic Oscillation. Links to background material and previous entries are below.

At the end of the previous blog I showed the following figure. The top panel shows the observed Arctic Oscillation Index from 1864 to 1960. The middle panel shows the observed Arctic Oscillation Index from 1864 to about 2000. The little number “r” in the panel is a measure of how well one year’s Arctic Oscillation Index is linked to or correlated with the previous year’s. A number close to zero is a measure of being unrelated. Prior to 1960, the observations were almost unrelated from year to year (r=-0.03). After 1960 there is a much stronger relation (r=0.4). Just looking at the graph after 1960, you can convince yourself that the Arctic Oscillation stays stuck in one mode or another for several years.

Figure 1: The top two plots in the figure show the observed Arctic Oscillation Index. The bottom plot shows a model simulation of the Arctic Oscillation Index. See text for more description. Thanks to Jim Hurrell

The bottom panel of Figure 1 shows a model simulation with the NCAR Community Atmosphere Model. In this model simulation the model’s carbon dioxide is held constant at levels prior to the industrial revolution, when man-made carbon dioxide was quite small. This simulation does not represent any particular year; it is 200 years which when taken together might look, statistically, like the atmosphere. An interesting feature of this simulation is that the Arctic Oscillation does look like the observations before 1960, but not after 1960. One possible suggestion of the reason why the model loses its ability represent the behavior of the Arctic oscillation is that carbon dioxide has increased enough to change the Arctic Oscillation.

I will come back to this below, but first a reminder of the other ideas I introduced in the middle part of the series. Most importantly, there is a stream of air that wants to flow around the North Pole. Likely in a world that has no mountains, no land and water sitting next to each other, then that air would actually circulate with the pole in the center. We live in a world with mountains and oceans and continents, which distort this stream of air. It’s a little like boulders in a creek, and water going around the boulders. The stream becomes wavy. There are other factors that also cause the air to be wavy, but I have introduced enough to make my points, and you can go back to the earlier blogs linked at the bottom for words and pictures. What causes the air to spin around the North Pole? The first thing to consider is the rotation of the Earth. The Earth’s atmosphere wants to line up with the rotation. Another important factor in determining the details of the air circulating around the North Pole is heating and cooling. The patterns of heating and cooling contribute to setting up high-pressure and low-pressure systems. Air flows from high to low pressure and as it flows towards low pressure it does its best to line up with the rotation of the Earth. This relation between high and low pressure and the Earth’s rotation is one of the most important features of the motion of the air in the atmosphere and the water in the ocean.

The way carbon dioxide changes the Earth’s climate is by changing the heating and cooling. A common comparison is to compare additional carbon dioxide to a a blanket which holds the Sun’s heat closer to the Earth’s surface. This blanket causes the Earth to heat up more at the pole than at the Equator. The poles are also special because the Sun goes down for the winter and it cools off. In fact, it gets very cold, and as discussed in the previous blogs, the stream of air that gets spun up isolates the pole enough to let the cooling really get going. With these changes to heating and cooling, if we add a lot of carbon dioxide to the atmosphere, then it is reasonable to expect that the Arctic Oscillation might change.

The studies prior to, say, 2008, suggested that the effect of carbon dioxide being added to the atmosphere would be to cause the Arctic Oscillation Index to become more positive. This would be the pattern of the Arctic Oscillation where the cold air is confined to the pole; that is, the less wavy pattern (scientific references: for example, Kuzmina et al. 2005 and the 2007 IPCC AR-4). The studies prior to 2008 support the idea that the additional carbon dioxide is a leading suspect in the changes after 1960 noted in Figure 1. That is, without carbon dioxide increasing in the simulation, the models cannot reproduce the statistical characteristics of the observations and with it increasing, they can.

Those pre-2008 studies, effectively, only considered increasing carbon dioxide. They did not represent the huge changes in the surface of the Arctic that have been observed. Notably, sea ice and snow cover have declined. These surface changes also cause changes in heating and cooling. The decline of sea-ice, for example, changes the surface of the Arctic Ocean from white to dark. This changes the surface from a reflector of energy to an absorber of energy. Sea ice is also a temperature insulator; hence, without the ice the ocean and atmosphere exchange heat more easily. There are many other changes as well, but all I want to do here is establish the plausibility that large changes at the surface are also likely to change the behavior of the Arctic Oscillation. Why? Changes in the patterns of heating and cooling, leading to changes in high and low pressure systems, which then with the influence of the Earth’s rotation, change the waviness of the stream of air around the Arctic.

There have been a series of papers in the past couple of years that suggest that the changes in sea ice and snow cover are having large effects on the weather in the U.S. If you look across these papers, then there is growing evidence that the meanders (or waviness) of the Arctic Oscillation are getting larger and that storms over the U.S. are moving more slowly. Here is a list of quotes from these papers.

From a paper I have previously discussed:

Francis and Vavrus (2012): Evidence linking Arctic amplification to extreme weather in mid-latitudes - “Slower progression of upper-level waves would cause associated weather patterns in mid-latitudes to be more persistent, which may lead to an increased probability of extreme weather events that result from prolonged conditions, such as drought, flooding, cold spells, and heat waves.”

Liu et al. (2012): Impact of declining Arctic sea ice on winter snowfall – “ … some resemblance to the negative phase of the winter Arctic oscillation. However, the atmospheric circulation change linked to the reduction of sea ice shows much broader meridional meanders in midlatitudes and clearly different interannual variability than the classical Arctic oscillation.”

Greene et al. (2012): Superstorm Sandy: A series of unfortunate events? - “However, there is increasing evidence that the loss of summertime Arctic sea ice due to greenhouse warming stacks the deck in favor of (1) larger amplitude meanders in the jet stream, (2) more frequent invasions of Arctic air masses into the middle latitudes, and (3) more frequent blocking events of the kind that steered Sandy to the west.”

There is some controversy about the work connecting the changes in the sea ice and snow cover to changes in the Arctic Oscillation and to changes in extreme weather in the U.S. (Barnes (2013): Revisiting the evidence linking Arctic amplification to extreme weather in midlatitudes, Francis response, and Freedman @ Climate Central ).

I think there is significant merit in the work that connects changes in the Arctic Oscillation to increases in carbon dioxide and related changes to the surface of the Earth. Part of my intuition comes from a career of working with atmosphere models. If a model is radiatively dominated, then the vortex over the pole is very strong. In this case, there is little waviness in the jet stream. This is analogous to the case of increasing carbon dioxide and the Arctic Oscillation becoming more common in its positive phase. If a model is less driven by radiative forcing, then it is easier for the waves that are initiated by the flow over the mountains to grow and distort the edge of the jet stream – more waviness. This is like the negative phase of the Arctic Oscillation. Though in the end it will require a careful calculation of the energy budget, the removal of sea ice from the surface of the Arctic Ocean allows more heat into the polar atmosphere, which means the radiative cooling will be less intense. Hence, the vortex will be weaker or the Arctic Oscillation will more commonly be in its negative phase. If there are changes in the Arctic Oscillation, which are realized as changes in the waviness and speed of the jet stream around the Arctic, then there will certainly be consequences to the weather in the U.S.

Potential changes in the character of the Arctic Oscillation are an important issue for those thinking about how to respond to climate change. The loss of sea ice is a large change, which will undoubtedly have important impacts in the Arctic. It is reasonable to expect large impacts on weather at lower latitudes, in the U.S., Europe and Asia. The change in the Arctic sea ice has happened very rapidly. This challenges the assumption often made in planning that climate change is a slow, incremental process. The weather of the here and now and/or the next fifty years, a common length of time for planning, is likely to be quite different from the past fifty years. Since we rely on our past experience to plan for the future, this is a direct challenge to our innate planning strategies. If we are cognizant of the possibility of significant changes to weather patterns on decadal lengths of time, then we can develop new planning strategies that will improve our resilience and make our adaptation decisions more effective.


Previous entries:

Climate Change and the Arctic Oscillation

Wobbles in the Barriers

Barriers in the Atmosphere


Definitions and Some Background

August Arctic Oscillation presentation

CPC Climate Glossary “The Arctic Oscillation is a pattern in which atmospheric pressure at polar and middle latitudes fluctuates between negative and positive phases.”

The views of the author are his/her own and do not necessarily represent the position of The Weather Company or its parent, IBM.

Reader Comments

Display: 0, 50, 100, 200 Sort: Newest First - Order Posted

Viewing: 243 - 193

Page: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11Blog Index

The problem with deniers

Member Since: December 31, 1969 Posts: Comments:
Quoting 237. yoboi:

Where do I begin this is ALL false.......

Member Since: December 31, 1969 Posts: Comments:
Earth Under Water

National Geographic

Synopsis: Miami, New Orleans and New York City completely under water; it's a very real possibility if sea levels continue to rise. In Earth Under Water we'll see these events unfold as leading experts forecast how mankind will be impacted if global warming continues. They'll break down the science behind these predictions and explore ways humanity could adapt, including engineering vast dams near San Francisco, or building floating cities outside of New York.

Member Since: December 31, 1969 Posts: Comments:
Five places already feeling the effects of climate change

Livescience.com | November 22, 2013

The effects of a warming planet are likely to be vast and varied — ranging from increased droughts and coastal flooding to reductions in snow and ice. But while most climate predictions look ahead to the potential risks 50 or 100 years from now, there are places around the globe that are already being impacted by global warming. Here are five places where climate change is already hitting close to home:

Great Barrier Reef

Satellite measurements have demonstrated that the waters of Australia's Great Barrier Reef have warmed by 0.36 degrees Fahrenheit (0.2 degrees Celsius) on average over the past 25 years. This warming has led to a decline in the amount of seafloor covered in thriving coral.

A 2012 study published in the journal Proceedings of the National Academy of Sciences found that half of the Great Barrier Reef was lost in the past 27 years.

Warming oceans, linked to rising emissions of carbon dioxide, increase the risk of coral bleaching — a phenomenon that disrupts the symbiotic relationship between corals and the organisms that live within their tissues and provide food the corals need to survive.

Higher-than-normal ocean temperatures cause corals to expel the tiny animals and algae that live inside them. This turns the corals white and places the reef-building animals — and the entire ecosystem — under stress.

Newtok, Alaska

Newtok, and many other villages in Alaska, are built atop permanently frozen soil, called permafrost. As ocean temperatures increase, Alaska's permafrost melts, causing the ground to erode and many of these remote, coastal towns to sink.

Newtok is located on the western coast of Alaska, on the edge of the rising Ninglick River. The flood-prone town already sits below sea level, and researchers have said the entire village could be underwater within a decade.

Now, members of the community are hoping to relocate Newtok's 350 residents to higher ground, at a site roughly 9 miles (14 kilometers) away. But there are financial and political barriers. For instance, the U.S. Government Accountability Office estimates that moving the town of Newtok could cost up to $130 million.

Mumbai, India

The Indian metropolis of Mumbai is one of the places at risk of dangerous and costly floods due to climate change, according to a report released earlier this year by the World Bank. Economists at the World Bank examined 136 large coastal cities, and evaluated their coastal defenses and level of protection.

The report identified Mumbai as one of the coastal cities that face a high risk of devastating floods due to global warming. Researchers found the city's existing defenses against flooding and storm surges are only designed to withstand current conditions, not for the anticipated rise in sea levels that will make future floods more devastating.

While coastal defenses are a start, "if they are not upgraded regularly and proactively as risk increases with climate change and subsidence, defenses can magnify — not reduce — the vulnerability of some cities," study leader Stephane Hallegatte, an economist at the World Bank, said in a statement.

The Alps

The Alps, one of the most famous mountain ranges in Europe, have long been a tourism hotspot, famous for their top-notch ski resorts and as a popular year-round destination for outdoors enthusiasts. But climatologists warn that global warming could spell trouble for the sprawling alpine region.

Since the late 19th century, temperatures in the Alps have been steadily rising, from an average yearly temperature of 49.3 degrees F (9.6 degrees C) in the late 1800s to today's average of 51.4 degrees F (10.8 degrees C), according to Gilles Brunot, a meteorologist based at the ski resort Chamonix-Mont-Blanc in southeastern France.

But concerns about global warming's effect on the Alps extend beyond the region's ski industry. About 40 percent of Europe's freshwater originates from the Alps, which stretch from Austria in the East to France in the West, dipping into parts of Italy and Monaco in the South. Climate change is threatening the area's water cycle, which includes patterns of precipitation, snow and glacier cover.

Gansu Province, China

Farmers across China's Gansu Province, one of the country's driest regions, are already struggling to cope with the effects of climate change, as droughts and arid land contribute to the region's vast poverty. The United Nations says warming temperatures are shrinking glaciers in central Asia and the Himalayas, which typically replenish China's rivers.

China recently completed its first National Census of Water, and found that as many as 28,000 of the country's rivers have disappeared since the 1990s. The study did not identify reasons for the loss of the rivers, but the research showed an alarming trend of dwindling water resources throughout the country.

China currently has 2,100 cubic meters (74,000 cubic feet) of water resources per person — roughly 28 percent of the global average, according to Reuters. But as the country's population grows, these supplies could dry up sooner than expected.
Member Since: December 31, 1969 Posts: Comments:
Lots o interesting stuff got trashed with the crash including Pat being hypocritical.
Member Since: December 31, 1969 Posts: Comments:
Quoting 227. Birthmark:

So there will be no evidence produced to support the "fine print" assertion? I ask to make sure you haven't forgotten.

Also, a search of Google Scholar shows no evidence of any peer reviewed work by Bob Tisdale in climate science or anything else.

Of course, WTFUWT is peer reviewed by Lord Monckfish.
Member Since: December 31, 1969 Posts: Comments:
Here you all go...enjoy. :D

Member Since: December 31, 1969 Posts: Comments:
Quoting 158. ILwthrfan:
Bob Tisdale did well in this piece, it even has some links down below as to the pros and cons to the data extraction and it's resulting interpretation. I believe Bob is somewhat neutral/anti-man made induced climate change...

Jared: I'm not sure that calling Bob Tisdale "neutral" would be an accurate statement.
Quoting 158. ILwthrfan:
...as they come to criticising some of the data, but doesn't try to hide things from you like some other major biases out there,
Hide things? To what are you referring?
Quoting 158. ILwthrfan:
While I don't agree with the majority of Bob's ideas, I do think this article looks at this particular idea with good [skepticism].
That would be a first for Mr. Tisdale. You have to remember, he believes that the planet can create and destroy heat energy, in violation of the one of the most fundamental tenets of physics. People who have trouble getting correct the basics from which all other concepts are derived, and they don't just get it wrong but they consistently and loudly proclaim that experts are wrong about it, well they get a lot more criticism in my book.
Quoting 158. ILwthrfan:Here is an abstract of the accuracy of the data itself. One topic discussed but not illustrated (until now in Figure 1) was that the annual variations in temperatures at depths between 700 and 2000 meters were in terms of hundredths if not thousandths of a deg C and that it was unrealistic to think we could measure the temperatures of the oceans at depth with that type of accuracy.

According to what? Is this how it seems to you, or do you base this on a scientific journal article that discusses the topic?
Member Since: Posts: Comments:
Where's the fine print?
I am waiting
Member Since: December 31, 1969 Posts: Comments:
Quoting 218. yoboi:

Bring it to Doug's blog so we are not off topic....I waxed BM before the crash....
No. Post it here. We won't be off topic - this is part of the flow of conversation. I don't know what you are talking about with "bm" and the crash, and I'm not really interested. Just put up or shut up.
Member Since: Posts: Comments:
Quoting 215. yoboi:

Do you really want to go down this path???????
Yes. Show us the fine print. It is what it is and I'm sure we're adult enough to take it.
Member Since: Posts: Comments:
Deleted because RevElvis beat me to it.
Member Since: December 31, 1969 Posts: Comments:
SuperStorms have Flood Insurance Rates Skyrocketing

Many older homes in flood zones have long benefited from a big subsidy that kept flood insurance rates very low. Starting next month, those homeowners will typically see annual rates jump more than 20 percent, including a fee for a new reserve fund. A late payment could cost them their subsidy immediately.

If the owner sells the home, the buyer will lose the subsidy. That could, as in one scenario, raise a premium that had been $1,400 a year to $9,500.

Travis wasn’t hopeful of a congressional reprieve in the next couple of weeks.

“Have I demoralized everyone here?” he asked.

Concern about rising flood insurance rates — triggered by the Biggert-Waters Act of 2012 — has been percolating for months. Now, just weeks before the law’s main provisions take effect, real estate agents and communities from Apollo Beach to Treasure Island are galvanizing, worried about falling property values, busted real estate sales and a crippling effect on the broader economy.

“This is a major change,” said Patty Latshaw of St. Petersburg-based Wright National Flood Insurance Co., the biggest writer of federal flood insurance in the country. “I’m just glad to see people are realizing what is going on and asking questions and becoming involved. Finally.”

For Cristy and Fred Assidy, reality hit too late.

After 15 years in their “starter home” in St. Petersburg’s Shore Acres, the couple was excited recently to close on a new home in Riviera Bay near Weedon Island.

Then came a shocker.

During this first year, their premium through the National Flood Insurance Program is a doable $1,700; next year it jumps to $17,000. For a house they bought for $205,000.

“This is going to devastate the real estate market here just when it’s barely making a comeback,” Cristy Assidy said. “People are going to leave the state in mass exodus.”

Member Since: Posts: Comments:
Summary on ocean acidification

A good review document is always hard to find, so here's one on ocean acidification by the International Geosphere-Biosphere Programme: Ocean Acidification Summary for Policymakers 2013.

Here are the first few points of the report:

Member Since: December 31, 1969 Posts: Comments:
Why America’s Major Sports Leagues Are Talking About Climate Change

Across Canada and the northern United States, thousands of children a year learn to love the game of hockey in the winter when they lace up their skates, grab their sticks, and head to the local pond to piece together a game on their frozen sandlots. They imitate the stars they see on TV, the Gretzkys and Crosbys and Ovechkins, and turn into lifelong players and fans.

But those kids are starting to run into a major problem: the frozen ponds they play on are less and less likely to form each winter, as a changing climate makes winter warmer and open ice more scarce.

That isn’t just bad news for kids who want to play the game. It’s also worrisome for the National Hockey League, a league already a distant fourth among America’s top four professional sports that depends on those pickup games and frozen ponds to help build new generations of fans and players. And the NHL isn’t alone. The NFL, NBA, Major League Baseball, and WNBA are all worried about the effects of environmental changes on their sports and the people who play them, which is why representatives from those five leagues plus the U.S. Olympic Committee joined Sen. Sheldon Whitehouse (D-RI) and Rep. Henry Waxman (D-CA) on Capitol Hill today to discuss their efforts to reduce energy usage and address climate change — and the efforts the federal government could take to do the same.

All of the representatives noted that their leagues felt a social responsibility for improving the environment. But they also stressed that it was good for business, and that in some ways their businesses depend on it. Warmer summers and polluted air have already made playing sports like baseball, football, and basketball outside more dangerous at certain times in the year. For the NHL, chief financial officer Craig Harnett said, fewer frozen ponds means less access for young people. All of that means fewer people can turn into fans and players through actual participation.


Member Since: Posts: Comments:

No time for delay in cutting greenhouse gas emissions, say IPCC scientists

"In other words, the longer we delay emissions cuts, the faster those cuts will have to be to stay within the two degree budget. And the faster cuts have to be, the harder they are to achieve."
Member Since: Posts: Comments:
From Climate Progress:

Oil Pipeline Explodes In China, Killing 35 And Setting The Ocean On Fire

A worker cleans up after China’s 2010 Dalian oil spill. CREDIT: ASSOCIATED PRESS

An oil pipeline exploded in Qingdao in China on Friday, killing 35 people and injuring 166 by the latest count. The explosion spilled oil into the ocean, and temporarily shut down one of China’s largest crude import terminals.

The pipeline is owned by Sinopec Corp, China’s largest oil refiner, and connects Huangdao to Weifang in the northeastern province of Shandong. It began leaking oil into Qingdao’s streets and port early Friday morning. The pipeline was shut off about 15 minutes after the leak began, and workers began repairs. Then, around 10:30 a.m. (9:30 p.m. Thursday EST) the oil caught fire and exploded in two locations.

The underground pipeline’s explosion opened a hole in the road that swallowed at least one truck, according to Reuters, and oil seeped into utility pipes under Qingdao. Gas and oil exploded and caught fire over the sea, according to the Qingdao Environmental Protection Bureau, and barriers were set up to keep it from spreading further than the 32,000 square feet already contaminated.

It is as yet unclear how Sinopec’s Qingdao refinery, which processes 240,000 barrels per day of imported crude, would be affected.

China’s last major oil spill occurred in 2010 in Dalian, another northeastern port, when two pipelines exploded, spilling between 18 and 27 million gallons of oil into the Yellow Sea, at least as much as the Exxon Valdez disaster.
Member Since: Posts: Comments:
Quoting 197. yoboi:

I drive an F-550 diesel that I use to pull my equipment it throws a lot of dark smoke don't really know how much Co2 I am emmiting....
I'm sure you don't care either... Ha Ha!
Member Since: December 31, 1969 Posts: Comments:
No time for delay in cutting greenhouse gas emissions, say IPCC scientists

As the end of the second week of climate talks draws nigh in Warsaw, a group of high profile scientists have laid out what needs to happen to stay below two degrees of global warming. The answer? Deep greenhouse gas cuts, and no more excuses for delay.

A matter of urgency

In its latest report, the Intergovernmental Panel on Climate Change (IPCC) said limiting global warming requires "substantial and sustained" cuts in greenhouse gas emissions.

In a new letter in Nature Climate Change, co-chair of the IPCC Thomas Stocker and Myles Allen from Oxford University consider two arguments used to suggest emission cuts can be delayed.

The first is that scientists have slightly lowered their assessment of how big the warming effect of carbon dioxide is on the planet - known as the climate sensitivity.

The other argument is that reducing emissions of pollutants like black carbon and methane is a more achievable way to limit total warming, instead of tackling carbon dioxide emissions.

The authors examine both arguments, concluding neither "buys time" to delay efforts to reduce carbon dioxide. Delaying emissions cuts now will make it harder to reduce warming in the long run, they say.

Peak and decline

Two degrees is the most widely accepted political threshold beyond which the risks posed by climate change are considered unacceptably high.

The IPCC calculates that to stay below two degrees of warming, carbon dioxide concentrations in the atmosphere must peak by about 2050. That means carbon dioxide emissions will have to peak much sooner.

The question the letter deals with is: What's the penalty for delaying cutting carbon dioxide emissions?

The cost of delay

Carbon dioxide has a predictable relationship with temperature. The warming we get is almost directly proportional to the total amount of carbon dioxide we release into the atmosphere.

Using this relationship, scientists can calculate a measure known as the transient climate response to carbon emissions ( TCRE). Technically-speaking, this is the change in average global surface temperature change for every trillion tonnes of carbon we emit.

In its latest report, the IPCC lowered its estimate of TCRE by about 25 per cent compared to the previous report released in 2007. But contrary to suggestions, this has little impact on the case for urgent mitigation, say the authors.

Why? A lower TCRE might mean the rate at which emissions need to be cut to stay under two degrees could be a little less drastic if we started now. But emissions are currently rising by 1.8 to 1.9 per cent per year, which is more than any reduction in warming that might come from a lower TCRE.

In other words, any possible benefit of a lower climate sensitivity is more than balanced out by the rate at which we're already putting carbon dioxide into the atmosphere, the authors say.

And our current rate of emissions means each year we delay cuts significantly ups the chances that we'll end up with more than two degrees warming. The authors say in the paper:

"If the same level of effort required in 2010 to limit carbon dioxide-induced warming to two degrees were applied starting in 2015, the resultant peak warming would be 10 per cent higher, at 2.2 degrees."

In other words, the longer we delay emissions cuts, the faster those cuts will have to be to stay within the two degree budget. And the faster cuts have to be, the harder they are to achieve.

Limiting peak warming to two degrees above pre-industrial means reducing carbon dioxide emissions by 2.4 per cent per year from 2015 (green). Delaying cutting emissions until 2025 means the same rate of cuts results in 2.5 degrees warming (yellow). Staying below two degrees would require much faster emissions cuts. Source: Stocker & Allen ( 2013).

Non-carbon sources

A second letter by Allen and colleagues, also published in Nature Climate Change, looks what the impact might be of cutting emissions of black carbon, methane and tropospheric ozone. These factors only have a short lifespan in the atmosphere, a few years to few decades.

The paper concludes that while cutting emissions of these factors might reduce the warming we see in the short-term by about 0.5 degrees Celsius, the impact on global temperature rise will be very small unless carbon dioxide is cut at the same time. The paper says:

"Proponents of climate mitigation through non-carbon dioxide measures rightly stress the difficulty of reducing carbon dioxide emissions: what this result illustrates is that the harder it turns out to be to mitigate carbon dioxide, the smaller the impact of non-carbon dioxide climate pollutants on peak warming, in both relative and absolute terms."

If we are confident of reducing carbon dioxide emissions fast enough to limit warming to two degrees, the extra 0.5 degrees saving from cutting non-carbon dioxide factors means we could potentially delay mitigation by 12 years, the authors conclude.

But the higher the limit we allow for total warming, the shorter the opportunity to delay. For peak warming of three degrees, the extra 0.5 degree saving equates to a nine-year delay, dropping to four years for four degrees of warming.

Dr Chris Huntingford of the NERC Centre for Ecology and Hydrology, co-author on the second letter, tells us:

"The argument implicit in this paper is that over the next few decades, the emphasis really should remain on tackling the longer-lived gases, and predominantly carbon dioxide".

The time is now

Both papers show there's very little room for manoeuvre in climate change mitigation - a strong point to be making with the closing stages of the international climate policy negotiations in Warsaw underway. If no progress is made towards legally-binding emissions reductions targets, it seems won't be for lack of supporting evidence about why we should get on with it.
Member Since: December 31, 1969 Posts: Comments:
IPCC sea level rise projection probably too low, says expert survey

A new survey of expert opinion suggests 21st century sea level rise might be higher than the latest UN climate report projects. More than two thirds of the researchers interviewed for the study said higher and faster rises are possible - implying the report's estimates could be too conservative.

Upper limit underestimated

The most comprehensive projections on sea level rise are those contained in the report from Intergovernmental Panel on Climate Change (IPCC). The IPCC evaluates evidence from all the published literature and combines the estimates into a single set of projections.

In its most recent report, the IPCC predicted sea levels are likely to rise by between 0.28m and 0.98m by 2100 - a range encompassing both its highest and lowest emissions scenarios.

But according to a new survey of sea level experts, that range might be an underestimate. Scientists from the Potsdam Institute of Climate Impact Research (PIK) asked 90 researchers from 18 different countries for their expert opinion on future sea level rise.

Two thirds of those questioned said they thought sea levels could rise higher than the IPCC's upper estimate for the end of the century.

When asked what they thought the likely range of sea level rise would be under a low emissions scenario, the experts came up with similar estimates to the IPCC.

When asked what they thought the likely range of sea level rise would be under a low emissions scenario, the experts came up with similar estimates to the IPCC.

When it came to predicting sea level rise under a high emissions scenario, the experts' assessment was considerably higher. They projected a maximum sea level rise of 1.2m by 2100:

Read more at Carbon Brief >>
Member Since: December 31, 1969 Posts: Comments:
Sea Level Rise Forecasts Helped by Insights Into Glacier MeltingLink

Nov. 22, 2013 — Predictions of sea level rise could become more accurate, thanks to new insight into how glacier movement is affected by melting ice in summer.

Studies of the Greenland ice sheet, including during a record warm summer, are helping scientists better understand how summer conditions affect its flow. This is important for predicting the future contribution made by melting glaciers to sea level rise.
Ice flows slowly from the centre of the Greenland Ice Sheet towards its margins, where it eventually melts or calves into the ocean as icebergs. Knowing how fast this movement occurs is essential for predicting the contribution of the ice sheet to sea level rise.
In summer, ice from the surface of a glacier melts and drains to the bed of the ice sheet, initially raising water pressure at the base and enabling the glacier to slide more quickly. It can, at times, move more than twice as fast in summer compared with winter, they found.
In 2012, an exceptionally warm summer caused the Greenland Ice Sheet to undergo unprecedented rates of melting. However, researchers have found that fast summer ice flow caused by significant melting is cancelled out by slower motion the following winter.
Scientists found that this is because large drainage channels, formed beneath the ice by the meltwater, helped to lower the water pressure, ultimately reducing the sliding speed.
The discovery suggests that movement in the parts of the ice sheet that terminate on land are insensitive to surface melt rates. It improves scientists' understanding of how the ice sheet behaves and curbs error in estimating its contribution to sea level rise in a warming world.
Scientists led by the University of Edinburgh gathered detailed GPS ice flow data and ice surface melt rates along a 115 km transect in west Greenland and compared ice motion from an average melt year, 2009, with the exceptionally warm year of 2012.
The study, carried out in collaboration with the Universities of Sheffield, Aberdeen, Tasmania and Newcastle, was published in Proceedings of the National Academy of Sciences and supported by the Natural Environment Research Council.
Professor Peter Nienow of the University of Edinburgh's School of GeoSciences, who led the study, said: "Although the record summer melt did not intensify ice motion, warmer summers will still lead to more rapid melting of the ice sheet. Furthermore, it is important that we continue to investigate how glaciers that end in the ocean are responding to climate change."

Journal Reference:
A. J. Tedstone, P. W. Nienow, A. J. Sole, D. W. F. Mair, T. R. Cowton, I. D. Bartholomew, M. A. King. Greenland ice sheet motion insensitive to exceptional meltwater forcing. Proceedings of the National Academy of Sciences, 2013; DOI: 10.1073/pnas.1315843110
Member Since: December 31, 1969 Posts: Comments:

“To announce that there must be no criticism of the President, or that we are to stand by the President, right or wrong, is not only unpatriotic and servile, but is morally treasonable to the American public.”
― Theodore Roosevelt

“Far better it is to dare mighty things, to win glorious triumphs, even though checkered by failure, than to take rank with those poor spirits who neither enjoy much nor suffer much, because they live in the gray twilight that knows neither victory nor defeat.”
― Theodore Roosevelt

“Every immigrant who comes here should be required within five years to learn English or leave the country.”
― Theodore Roosevelt
Member Since: Posts: Comments:

Viewing: 243 - 193

Page: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11Blog Index

Top of Page

Dr. Ricky Rood's Climate Change Blog

About RickyRood

I'm a professor at U Michigan and lead a course on climate change problem solving. These articles often come from and contribute to the course.

Ad Blocker Enabled