December 6, 2023 by Janet Chikofsky
Three new graphs in En-ROADS explore the financial effects of energy policies and the impact of climate change on the number of years with extreme heat.
En-ROADS now displays the market prices of oil and natural gas, in addition to the market price of electricity. These prices can be found under Graphs > Financial and reflect the impact of taxes, subsidies, and carbon pricing in the Current Scenario and Baseline Scenario.
The market price graphs can be useful for discussing the equity implications of policies on consumers and households. For example, a carbon price of $150/ton CO2 lowers temperature but also increases the market price of oil. The market price of oil is directly proportional to how much it costs to fill a vehicle’s gasoline tank, so rising oil prices mean higher transportation costs. Lower-income households spend a much larger proportion of their income on energy compared to higher-income households, and these rising prices are likely to burden them the most.1
Keep in mind that the impact of these market prices on households will also be affected by factors such as energy efficiency and electrification. An increase in energy efficiency would relieve some of the burden caused by increased energy prices from pricing carbon or otherwise taxing energy supplies. If the ratio of increase in transport energy efficiency is higher than the ratio of increase in the price of energy, the net burden would actually go down.
Climate change is increasing the number and severity of extreme heat events around the world, highlighted by record-breaking heatwaves in Madagascar and Brazil in recent months. Under Graphs > Impacts, En-ROADS now includes a “Frequency of Extreme Heat” graph showing the projected change in the number of years with at least one extreme heat event. These extreme heat events would happen once in 50 years if there were no climate change.
In this graph, the dark dots represent the number of years with daily maximum temperatures higher than the extreme heat threshold, while light dots represent years with daily maximum temperatures lower than the extreme heat threshold. The “extreme heat threshold” is the maximum daily temperature that occurred between 1850 and 1900. Clicking “Show more…” in the lower right corner enlarges the graph and reveals the frequency of extreme heat in the 1850-1900 period, which is representative of the pre-industrial era.
Global average surface temperature is currently 1.3°C warmer than it was during the pre-industrial era. At this temperature, extreme heat that occurred once in 50 years in the pre-industrial era is now likely to occur in 7 years out of 50. Another way to think about this is the probability of extreme heat occurring in a given year. In the pre-industrial era, there was a 1 in 50, or 2%, probability of an extreme heat event occurring in a given year. Today, there is a 14% probability (7 in 50) of extreme heat occurring in a given year, and in the Baseline Scenario in 2100, there is a 58% probability (29 in 50) of extreme heat.
As you build a scenario of climate action, notice the frequency of extreme heat events decreases in the Current Scenario. For example, a carbon price of $150/ton CO2 reduces the frequency of extreme heat events in 2100 from 29 years out of 50 to 19 years out of 50.
Extreme heat events may have major equity implications, several of which are demonstrable in En-ROADS. Extreme heat events disproportionately affect lower-income and marginalized communities, who are more likely to live or work without access to air conditioning, live in neighborhoods with fewer trees to cool them, and have less access to medical care. Additionally, a global measure like the frequency of extreme heat is not distributed evenly across the world. As shown in the “Additional Deaths from Extreme Heat” graph, also found under Graphs > Impacts, the increase in deaths attributable to extreme heat due to climate change varies across different regions.
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