Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.
By: Dr. Jeff Masters , 11:42 AM GMT on March 31, 2014
Climate change is already having "widespread impacts", and has the potential to worsen global hunger, water availability, disease, drought, flooding, refugees, and war in the coming decades if we do nothing to reduce it, said the Intergovernmental Panel on Climate Change (IPCC) today, in the latest installment of their once-every-seven-year report on the climate. Today's report on climate change impacts and how we can adapt to them warned that "throughout the 21st century, climate-change impacts are projected to slow down economic growth, make poverty reduction more difficult, further erode food security, and prolong existing and create new poverty traps." Today's report by the Nobel-prize winning group of scientists was the second of four parts. Part 1, released in September 2013, covered the physical science behind climate change. Part 3 (due out in mid-April, 2014) will discuss how we can mitigate (reduce) climate change impacts. Part 4 (due out in early November, 2014) will present a grand summary of Parts 1, 2, and 3. Some key themes from today's report:
Food supplies will tighten. To me, the most important finding of the report is the climate change's threat to reduce global food supplies, which have already been negatively impacted, and are at risk to get much worse: “Based on many studies covering a wide range of regions and crops, negative impacts of climate change on crop yields have been more common than positive impacts. Climate change has negatively affected wheat and maize (corn) yields for many regions and in the global aggregate." For the future, the report acknowledges that some areas will likely see increases in food production, due to increased CO2 in the air and more favorable precipitation, but the overall global trend in food supplies will likely be downward (Figure 1.) This downward trend in yields will occur in the face of rapidly increasing demand, as the population grows by 2 billion, resulting in "increased likelihood of under-nutrition resulting from diminished food production in poor regions."
Figure 1. Summary of projected changes in crop yields, due to climate change over the 21st century. The figure includes projections for different emission scenarios, for tropical and temperate regions, and for adaptation and no-adaptation cases combined. Over the period 2010 - 2029, about as many scenarios predict an increase in global crop yields as predict a decrease. However, beyond 2030, more than twice as many scenarios predict a decrease versus an increase. Relatively few studies have considered impacts on cropping systems for scenarios where global mean temperatures increase by 4°C or more. For five time frames in the near-term and long-term, data (n=1090) are plotted in the 20-year period on the horizontal axis that includes the midpoint of each future projection period. Changes in crop yields are relative to late-20th-century levels. Data for each time frame sum to 100%. Image credit: IPCC.
Water availability to people will decrease, as wet areas get wetter and dry areas get drier. Not only does climate change pose huge risks to our food supply, it also threatens water availability. “The fraction of global population experiencing water scarcity and the fraction affected by major river floods increase with the level of warming in the 21st century.”
We're not adapting fast enough to avoid serious damage. The report talks about "adaptation deficits", as demonstrated by our relatively poor ability to respond to impacts from from recent extreme climatic events. "Climate-change-related risks from extreme events, such as heat waves, extreme precipitation, and coastal flooding, are already moderate (high confidence) and high with 1°C additional warming (medium confidence)." IPCC author and Princeton Professor Michael Oppenheimer put it more succinctly to the Associated Press: “We’re all sitting ducks.”
Poor people are most at risk from climate change. Climate-related hazards constitute an additional burden to people living in poverty, acting as a threat multiplier.
Climate change increases the risk of violence. For the first time, the IPCC lays out the case that climate change can add a destabilizing factor that can make violence more likely in countries with social and economic inequalities. "Climate change can indirectly increase risks of violent conflicts in the form of civil war and inter-group violence by amplifying well-documented drivers of these conflicts such as poverty and economic shocks."
Climate change increases the risk of more refugees. "Displacement risk increases when populations that lack the resources for planned migration experience higher exposure to extreme weather events."
Climate change will be costly. Though the uncertainties are high, the costs for an additional 2°C rise in temperature are thought to be between 0.2 and 2.0% of global GDP. "Losses are more likely than not to be greater, rather than smaller, than this range, since it is difficult to account for catastrophic changes, tipping points, and many other factors."
Human health will suffer. "Throughout the 21st century, climate change is expected to lead to increases in ill-health in many regions and especially in developing countries with low income…the magnitude and severity of negative impacts are projected to increasingly outweigh positive impacts. Examples include greater likelihood of injury, disease, and death due to more intense heat waves and fires; increased likelihood of under-nutrition resulting from diminished food production in poor regions; risks from lost work capacity and reduced labor productivity in vulnerable populations; and increased risks from food- and water-borne diseases and vector-borne diseases" (like malaria.)
We can take action to reduce these substantial risks. "Mitigation is considered essential for managing the risks of climate change." Mitigation refers to human actions to reduce climate change. Burning fewer fossil fuels and thus putting less CO2 in the air is essential to mitigating climate change. We should view the next few decades as the era of ‘climate responsibility’, when we can make a huge difference to keep our future climate livable. The report emphasizes that if greenhouse gases continue to rise, the world can expect an additional 6 - 7°F (3.5 - 4°C) of warming by 2100, instead of the international goal of keeping this rise less than 2°F (1.2°C). Princeton's Dr. Oppenheimer compared these two choices as "the difference between driving on an icy road at 30 mph versus 90 mph. It's risky at 30, but deadly at 90." Uncertainty is not a reason to delay climate action, and it is cheaper to act now on climate change than to delay. The International Energy Agency said in 2013 that in order to keep global warming less than 2°C above pre-industrial levels, "Delaying stronger climate action until 2020 would avoid $1.5 trillion in low-carbon investments up to that point, but an additional $5 trillion would then need to be invested through to 2035 to get back on track." The latest IPCC findings will be a key discussion topic for world leaders at a September 23, 2014 Climate Summit in New York City, hosted by UN Secretary-General Ban Ki-moon. The summit aims to mobilize political will to pave the way for an ambitious global legal climate agreement to be signed at the critical December 2015 Conference of Parties (COP) negotiations in Paris.
Associated Press coverage of the IPCC Part 2 report.
New Blockbuster IPCC Climate Report: Comprehensive, Authoritative, Conservative, my September 2013 post on who the IPCC is, and how they write their reports.
Landmark 2013 IPCC Report: 95% Chance Most of Global Warming is Human-Caused, my September 2013 post on Part I of the 2013 - 2014 IPCC report.
Video 1. The IPCC released this video to accompany today's release of their 2014 Impacts and Adaptation report.
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