More Intense Heat Waves. Outside the Arc- tic, the fastest warming is projected to occur NARROWING CLIMATE in central and eastern North America, central UNCERTAINTIES Europe, the Mediterranean region (including southern Europe, northern Africa and the Near Even though the Earth’s climate is an extremely complex, East), western and central Asia, and southern interconnected system that is sensitive to small chang- Africa. The tropics especially are expected to es, increased data collection, computing power, and experience widespread extreme heatwaves. sophisticated modeling means that our understanding of Extreme Weather and Weather Patterns. climate change has become increasingly strong. Several Warming temperatures are likely to create the areas of research are attempting to reduce uncertainty: atmospheric conditions for more intense and Attribution: Scientists are improving their ability to in some cases, more frequent natural disas- attribute specific events after the fact to climate change. ters, including stronger hurricane-strength This nascent field, known as extreme event attribution, storms, coastal 昀氀ooding, storm surges, and could change how publics perceive the growing threat droughts. Traditional weather patterns are also changing—for example, dry areas are ex- and provide a basis for developing countries or impact- pected to become drier, wet areas will become ed communities to claim damages from high emitting wetter, and precipitation will be less frequent countries or their government. but more intense in some areas. Feedback Loops: Scientists currently have a difficult ADDING TO ENVIRONMENTAL DEGRADATION time projecting when and to what extent positive During the next two decades, population feedback loops will drive further temperature increases growth, rapid urbanization, and poor land and risk runaway warming. For example, the loss of and resource management will increasingly reflective sea ice will reveal more of the ocean surface, intersect with and exacerbate climate change which is dark and absorbs heat faster, in turn causing even more sea ice to melt. Another concerning feedback e昀昀ects in many countries, particularly in the loop is methane, a powerful greenhouse gas that is developing world. With coastal cities growing, released from wetlands, permafrost, and ocean hydrates more people than ever will be threatened by a in response to increased temperatures. combination of storm surges and sea level rise that worsen existing coastal erosion. Land Degradation. The expansion and un- sustainable management of agriculture and forestry practices degrade land, and both con- and thickness. Globally, the sea level has risen tribute to and intensify the e昀昀ects of climate an average of 8 to 9 inches since the late 19th change. A 2019 study found that global defor- century; estimates of rise in the next 20 years estation and land degradation each contribut- range from another 3 to 14 inches, which ed to about 10 percent of all human-induced would create additional problems for low lying greenhouse gas emissions by releasing carbon coastal cities and islands. On land, thawing stored in the trees and the soil. permafrost is likely to cause increasing dam- Water Misuse. Poor water governance within age to infrastructure, including transportation and between states will remain the primary systems, pipelines, and power plants. 34 GLOBAL TRENDS 2040