Further information

The maps show the chance that regional-scale aggregated impacts exceed defined values: population exposed to river flooding increases by over 25%, population in water stress increases by over 10%, over 20% of cropland experiences a decline in suitability, and more than 25% of population is exposed to heatwaves. Chances are derived from the distribution of impacts in a given year and assume that all of the individual relationships between global mean temperature change and impact are equally plausible. The thresholds are arbitrarily defined, and are all expressed as percentages of some measure of exposure: – for the water and flood indicators they are the same as those used by King et al. (2015) Climate Change: A Risk Assessment . Percentage thresholds are used to enable comparisons between regions and therefore to illustrate the regional variation in impact, but the same percentage thresholds translate into different absolute thresholds in different regions. The chances are calculated assuming population follows SSP2 and the chances would be different under different scenarios.

How do we estimate climate impacts from each temperature change pathway?

Global-scale impacts under a specific climate pathway for a given year are estimated by combining the distribution of global mean surface temperature change produced by the simple climate model with a set of “damage functions” which define relationships between global mean surface temperature and impact. Different damage functions represent different regional changes in temperature and rainfall associated with a given change in global mean surface temperature. The estimated distribution of impacts in a given year under a specific pathway therefore incorporates uncertainty in (i) the change in temperature under that pathway and (ii) the regional distribution of changes in climate. The values in the infographic chart are the median-of the distribution of impacts in a given year. The impacts across all scenarios assume a ‘middle-of-the-road’ population growth scenario (scenario SSP2) throughout the 21st century, with approximately 9 billion people in 2100.

 

What emissions pathways would lead to the 2°C and 5.2°C scenarios?

The  5.2°C scenario is based on the “Representative Concentration Pathway (RCP) 8.5” scenario from the IPCC’s Fifth Assessment Report, updated to include recent global GHG emissions estimates.

The 2°C scenario assumes that emissions are reduced sufficiently for there to be a 50% chance that the rise in temperature by 2100 will be less than 2oC.

 

Regional boundaries

Due to the nature of the analysis there appear to be big apparent jumps across regional boundaries. This arises because the maps do not show a continuous geographic variable. Rather, the same climate change is projected onto population which varies across space: they show discrete regional totals over areas of different sizes and configurations. The Alaska/rest of USA/Canada discrepancy arises because Alaska/rest of USA are one region, and Canada is another.

 

Regions

The impacts shown in the infographic were calculated for the regions below.

West Africa Benin, Burkina Faso, Gambia, Ghana, Guinea, Guinea-Bissau,  Ivory Coast, Liberia, Mali, Mauritania, Niger, Nigeria, Senegal, Sierra Leone, Togo
Central Africa Cameroon, Cape Verde, Central African Republic, Chad, Congo, DR Congo, Equatorial Guinea, Gabon, Sao Tome and Principe,
East Africa Burundi, Djibouti, Ethiopia, Eritrea, Kenya, Rwanda, Somalia, Uganda
Southern Africa Angola, Botswana, Lesotho, Madagascar, Malawi, Mauritius, Mozambique, Namibia, Seychelles, South Africa, Swaziland, Tanzania, Zambia, Zimbabwe, plus western Indian Ocean islands
North Africa Algeria, Libya, Morocco, Western Sahara, Sudan, Tunisia, Egypt
Middle East Bahrain, Oman, Saudi Arabia, Qatar, United Arab Emirates, Yemen, Iraq, Israel, Jordan, Kuwait, Lebanon, Occupied Palestinian Terr., Syria, Turkey
South Asia Afghanistan, Bangladesh, Bhutan, India, Iran, Maldives, Nepal, Pakistan, Sri Lanka
South East Asia Brunei, Cambodia, East Timor, Indonesia, Laos, Malaysia, Myanmar, Philippines, Singapore, Thailand, Vietnam
East Asia China, Japan, Rep. of Korea, Dem. Rep. of Korea, Mongolia, Taiwan
Central Asia Kazakhstan, Kyrgyz Rep., Tajikistan, Turkmenistan, Uzbekistan
Australasia Australia, New Zealand, Papua New Guinea, Pacific Ocean islands
Western Europe Andorra, Austria, Belgium, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Liechtenstein, Luxembourg, Malta, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland, UK
Central Europe Albania, Bosnia-Herzegovina, Bulgaria, Croatia, Cyprus, Czech Rep., Estonia, Hungary, Latvia, Lithuania, Poland, Romania, Slovakia, Slovenia, Macedonia,  Montenegro, Serbia
Eastern Europe Azerbaijan, Armenia, Belarus, Georgia, Moldova, Russia, Ukraine
Canada Canada
USA USA
Central America Belize, Costa Rica, Cuba, El Salvador, Guatemala, Honduras, Nicaragua, Mexico, Panama, and the Caribbean Islands
Brazil Brazil
South America Argentina, Bolivia, Chile, Colombia, Ecuador, French Guiana, Guyana, Paraguay, Peru, Suriname, Uruguay, Venezuela

No simulation for Greenland

 

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