Rising Temperatures

The Earth is unequivocally warming. One of the notorious effects of climate change is global warming; average global temperatures are increasing and long-term heat waves are growing longer and more dangerous. Global warming, caused by the highest levels of greenhouse gases in the atmosphere in the past 400,000 years,[1] has already caused an increase in average global temperature, and this trend is projected to continue. Current climate models project anywhere from a 2-4℃ increase in global average temperatures in the next several decades,[3] which will result in an increase in sea level rise and more dangerous summer heat waves. In addition to an overall higher temperature, heat waves are increasing in frequency and severity.[2] Heat waves are a prolonged period of increased heat, which can cause heat stress on the body, which often takes form of heat stroke.[2] When considering the impacts of heat on people it is important to consider the heat index. The heat index factors in humidity to give a more accurate “feels like” temperature that better represent the amount of heat stress a person will experience. Due to climate change, temperatures using the heat index will rise above dangerous levels more often and for longer periods of time.[2]

This amount of heat has the capacity to cause serious damage to humans, infrastructure, agriculture, and the environment as a whole. Extreme heat will have severe consequences on human life as we know it, affecting both MIT and Bangladesh in different ways, leaving us with no choice but to adapt to the changing times.

 

Figure 1: Projected sea level rise and northern hemisphere summer heat events over land in a 2℃ world (upper panel)

and a 4℃ world (lower panel)
Source: The World Bank, Bangladesh – Economics of Adaptation to Climate Change[3]

Rising Temperatures at MIT

Due to climate change Cambridge will experience rising temperatures and an increase in both the duration and frequency of heat waves. In the Cambridge area, the annual number of days over 90 degrees Fahrenheit could triple by 2030, and increase six-fold by 2070 [Figure 2].[4] This will be amplified by the urban heat island effect, which leads to uneven heating in urban environments due to impermeable, dry surfaces [Figure 3]. On a hot, sunny, summer day, the sun can heat urban surfaces, including roofs and pavement, to temperatures 50–90°F hotter than the air.[5] The increase in temperature will impact the environment, residents, and infrastructure of Cambridge.

Figure 2: Projected increase in days over 90℉

Source: Climate Change Vulnerability Assessment Part 1[4]

Figure 3: Future conditions with heat island effect and heat index for 2030 and 2070

Source: Climate Change Vulnerability Assessment Appendix D[6]

The increase in temperatures will have a significant impact on the length and severity of droughts. Short, seasonal droughts are already common in the northeast, but conditions are expected to get worse. Warmer temperatures will lead to higher evaporation rates and earlier, smaller snow melt.[7] The negative impacts droughts have on Massachusetts include lack of water availability, increased local species extinctions and decreased plant growth.

Rising temperatures will also negatively affect public health. Heatwaves lead to heat related illnesses including heat exhaustion and heat stroke especially among vulnerable populations such as children, elderly, socioeconomically disadvantaged groups, socially isolated and people with pre-existing health conditions such as diabetes. Heat has been the leading cause of death among natural disasters in the United States since 1988, however, it is also the most well understood, measurable, and preventable.[4] Additionally, higher temperatures could result in an increased likelihood of getting vector borne diseases. Changes in the environment including rising temperatures and flooding will lead to changes in seasonal and topological distributions of vectors including ticks, mosquitoes, and fleas.  For example, exposure to Lyme carrier ticks will increase due to longer periods of activity and expansion northward [Figure 5].[8] 

Figure 5: Expansion of cases of Lyme disease

Source: The Impacts of Climate Change on Human Health in the United States: A Scientific Assessment[8]

In addition to public health risks, higher temperatures will affect infrastructure including the transit, critical services and potentially energy resources. Both the subway and commuter rail are vulnerable to heat and could be at risk of failure during heat waves. Extreme heat could cause tracks to buckle or damage electrical equipment. Additionally, critical services such as police and fire departments are susceptible to extreme heat. Extreme heat events lead to higher demand for services, while the heat could damage heat sensitive equipment and the health and safety of first responders. Many fire stations in Cambridge do not have air conditioning.[4] Although energy resources are not currently highly vulnerable to heat because of backup measures in place if equipment fails, rising temperatures will increase the likelihood of failure. Higher temperatures reduce the productivity of natural gas, oil and nuclear power plants due to reduced efficiency of fuel burning, turbines, boilers and generators. Specifically for nuclear, a 1.8°F (1°C) rise in ambient air temperature can result in more than a 2% decrease in output.[9] In July of 2017 89.8% of Massachusetts energy came from natural gas, oil or nuclear power plants.[10] Furthermore the heightened demand for air conditioning during heat waves puts strain on the energy resources. If the power grid is unable to produce the amount of electricity demanded a blackout will occur. While blackouts are currently uncommon, the Independent System Operator New England, which oversees the electricity grid, went into this past summer preparing for tight supply conditions due to potential peak summer conditions.[11] If supply is currently tight and rising temperatures will increase demand while reducing the supply, blackouts are going to happen more frequently. Power failure could significantly impact Cambridge economically with losses of $43 million per day.[4]

Solutions Addressing Rising Temperatures at MIT

Adapting to Increasing Spread of Disease Carbon Tax Emergency Planning Education Energy-Efficient Heating and Cooling Systems Green Space Heat Wave Response Net-Zero Buildings Addressing the Effects of Acid Rain Renewables Road Material

Rising Temperatures in Bangladesh

Climate data suggest that extreme heat and climate change in general will hit South Asia especially hard. Some of the hottest temperatures have been recorded in these areas. Wet-bulb temperature (TW) is often used to measure heat because it takes into account heat due to air temperature and heat due to humidity. TW is measured as the lowest temperature that can be achieved by evaporating water out of a parcel of air until it is cooled completely,[2] and it is always lower than the outside air temperature. High values of TW imply high temperatures and high humidity, and when this temperature is exceptionally high, there is a very small difference between internal body temperature and the outside air. This is dangerous because your body needs to be surrounded by a cooler environment in order to release heat and regulate body temperature. When this ability to regulate heat is disrupted significantly, i.e. the body is unable to stay in the safe zone of +/- 1.8℉ from the healthy body temperature of 98.6℉, the heat starts to impair normal physical and mental functions[2]. Records show that Bangladesh and the surrounding region reach up to a TW of 82℉ (28℃) during severe heat waves, which is considered dangerously high [Figure 6]. The average number of days of heat waves per year is currently 60 days, but is expected to increase to over 100 days for optimistic models, and 300 days for a high emission models.[12] Spending more than a few hours in 95℉ (35℃) wet-bulb temperature is the absolute highest temperature that a human body can handle and can be fatal to even the most healthy individuals. This is because at this TW, metabolic heat cannot be released by the body[2] and will immediately degrade physical and mental faculties. According to climate models, wet-bulb temperatures in Bangladesh are only expected to worsen [Figure 7], reaching dangerously close to this fatal level during severe heat waves. Even the most optimistic models show close to fatal-level maximum temperatures within the next 30 years.

Figure 6: Conversion table between relative humidity and temperature (TW), colored by stress risk levels. Source: Eun-Soon Im, Deadly heat waves projected in the densely populated agricultural regions of South Asia[2]

 

Figure 7: Projected and historical wet-bulb temperatures in South Asia

Source: Eun-Soon Im, Deadly heat waves projected in the densely populated agricultural regions of South Asia[2]

In addition to deaths caused directly by heat waves, many other sectors of Bangladesh will be affected by an increase in temperatures. Agriculture will be significantly harmed by an increase in heat waves. An overall increase in temperature changes the environment that wildlife and plants are adapted to, creating less efficient growing conditions and smaller crop yields.[3] Heat also often leads to drought, and climate models predict an increase in consecutive days of drought from the current average of 70 days to 85 days in 2100.[12] This will put considerable strain on water resources for irrigation and for personal use, hurting agricultural and the community. Economically, Bangladesh will be hurt as severe heat directly leads to loss of productivity, especially for heavy outdoor labor.[12] Heat stress is expected to decrease annual daily work hours by 28% by 2100 if global temperatures rise by 4℃.[12] All of these factors affect the entire country, but unfortunately, especially in Bangladesh where income inequality is already an issue, and the effects of extreme heat and drought will exacerbate this problem.[3] Poor farmers are the least equipped to upgrade their irrigation strategies in order to improve yield and expected income, and people who live in slums are unable to able to hide in air-conditioned areas during severe heat waves. Preparing the country for extreme heat is a humanitarian crisis that must be dealt with.

Solutions Addressing Rising Temperatures in Bangladesh

Crop Selection and Genetic Engineering Community-Based Adaptation Green Roofs Irrigation Protecting and Expanding Existing Mangroves Reforestation Sustainable Land Management

 

By Sheila Kennedy-Moore and Sarah Weidman

 

References

  1. Global Climate Change: Vital Signs of the Planet. (2017). NASA. Retrieved from https://climate.nasa.gov
  2. Im, Eun-Soon, Jeremy Pal, and Elfatih Eltahir. (2017). Deadly heat waves projected in the densely populated agricultural regions of South Asia. Science Advances 3, 1-44.
  3. The World Bank. (2010). Bangladesh – Economics of Adaptation to Climate Change (No. 70266) (pp. 1–130). The World Bank.
  4. Climate Change Vulnerability Assessment Part 1. (2015). Retrieved from http://www.cambridgema.gov/CDD/Projects/Climate/~/media/307B044E0EC5492BB92B2D8FA003ED25.ashx
  5. Heat Island Impacts. (2017). Environmental Protection Agency. Retrieved from https://www.epa.gov/heat-islands/heat-island-impacts
  6. Climate Change Vulnerability Assessment Appendix D: Urban Heat Island Protocol for Mapping Temperature Projections. (2015). Retrieved from https://www.cambridgema.gov/cdd/projects/climate/~/media/007A3255079540399C25A78038B961A9.ashx
  7.  Massachusetts Wildlife Climate Action Tool. (n.d.). Drought. Retrieved  from http://climateactiontool.org/content/drought
  8. Crimmins, A., J. Balbus, J.L. Gamble, C.B. Beard, J.E. Bell, D. Dodgen, R.J. Eisen, N. Fann, M.D. Hawkins, S.C. Herring, L. Jantarasami, D.M. Mills, S. Saha, M.C. Sarofim, J. Trtanj, and L. Ziska, Eds. (2016). The Impacts of Climate Change on Human Health in the United States: A Scientific Assessment. U.S. Global Change Research Program. Retrieved from http://dx.doi.org/10.7930/J0R49NQX
  9. Aivalioti, S. (2015).  Electricity Sector Adaptation To Heat Waves. Columbia Law School. Retrieved from http://columbiaclimatelaw.com/files/2016/06/Aivalioti-2015-01-Electricity-Sector-Adaptation-to-Heat-Waves.pdf
  10. U.S. Energy Information Administration. (2017). Massachusetts State Profile and Energy Estimates. Retrieved November, 2017, from https://www.eia.gov/state/data.php?sid=MA  
  11. ISO New England. (2017, April). Managing Power Grid Operations This Summer. Retrieved from https://www.iso-ne.com/static-assets/documents/2017/04/20170426_pr_managing_power_grid_operations_this_summer.pdf
  12. Climate and Health Country Profile: Bangladesh. (2015). World Health Organization. Retrieved from http://www.searo.who.int