Aiming for an average global warming target of 2 degrees will still allow devastating heatwaves to occur.

Recent policy discussions on climate change have focused on limiting global average temperature increases. For instance, the European Union has set a goal of limiting global warming to 2°C. However, this goal represents a global average—regional and local temperature changes may vary, and substantial increases in regional extreme heat events could occur, possibly with serious consequences for some communities.

To help inform discussion, Clark et al. (2010) used an ensemble of climate simulations to study the potential increase in extreme heat waves under a scenario in which global warming is limited. They found that even if average warming is limited to 2°C, estimated increases in temperature during the hottest days range from 2°C to 6°C for parts of Europe, North America, and Asia. The researchers also investigate the sources of uncertainty in estimates of regional changes.

Citation: Clark, R. T., J. M. Murphy, and S. J. Brown (2010), Do global warming targets limit heatwave risk?, Geophys. Res. Lett., 37, L17703, doi:10.1029/2010GL043898.

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Heat waves, or extreme heat events, are characterized by several days of temperatures greater than 90° F; warm, stagnant air masses; and consecutive nights with higher–than-usual minimum temperatures. As a result of climate change, heat waves are expected to increase in severity and frequency, particularly in the northern latitudes. The nature of the temperature shifts brought by climate change, which include both a shift in the average temperature overall as well as an increase in temperature variability, are depicted in the graphs below. The images show that there is likely to be much more hot weather with climate change, and more record hot weather, as well.

Effects of increased average temperatures and climate-changed induced temperature variability on the number of hot days.

Heat waves are already the most deadly weather-related exposure in the U.S., and account for more deaths annually than hurricanes, tornadoes, floods, and earthquakes combined. Children and older adults are at greater risk from heat. Other risk factors for heat-related death include living alone, lack of air-conditioning, and use of certain medications. Additionally, there is an element of adjustment to heat as body processes change to compensate for increased temperatures; this can be protective during heat waves.

Climate change will bring more heat waves to the U.S. Increases in the number of people living in cities, as well as population aging, will further increase heat-related health risks. Studies suggest that, if current emissions hold steady, excess heat-related deaths in the U.S. could climb from an average of about 700 each year currently, to between 3,000 and 5,000 per year by 2050.

Effective strategies have been identified for preventing heat-related illness and death among individuals and populations. Individually, gaining access to cooler temperatures, usually achieved through air conditioning, is key to preparing for heat waves. Checking elderly and homebound neighbors, relatives, and acquaintances during heat waves can be life-saving. Avoiding or rescheduling strenuous activities during heat waves, drinking lots of water, and dressing in light-colored, loose fitting clothing are all important behavior changes.

Heatwaves due to climate change will be more frequent, hotter and longer.

On a community level, municipal heat response plans can be very effective, and vulnerability mapping, a process that highlights the locations of vulnerable populations, can target efforts even more effectively. Urban planning that increases green space, reduces heat build-up in buildings and other structures, and decreases the size and intensity of the urban heat island is also an effective strategy.

Learn More:

CDC e-learning course on heat-related illnesses.

CDC Extreme Heat Guide.

Source: http://www.cdc.gov/climatechange/effects/heat.htm

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