World Bank Report on Climate Change: Avoiding 4°C Warmer World

1. Introduction

On Monday, November 26th, the World Bank came out with a report called Turn Down the Heat: Why a 4°C Warmer World Must be Avoided. A copy of this report can be seen at the following web address.

The report was prepared for the World Bank by the Potsdam Institute for Climate Impact Research and Climate Analytics. The world is already 0.8°C warmer compared to pre-industrial levels. However even if the emission reductions pledged by countries as part of the UN Framework Convention on Climate Charge are adhered to, the warming will continue to 3.5° to 4°C. The purpose of this report is to give an idea of what a 4.0°C warmer world would be like, and to urge the global community to take stronger measures than those currently in place in order to limit the global warming to under 2°C. Of course, if the reductions pledged by countries are not adhered to, an even more extreme scenario of 6°C or greater is possible. For perspective, you should realize that 4°C is the difference between the temperature during the last ice age and that of today.

The reason why the World Bank is getting involved in the climate change debate is because is funds development in developing countries, and it turns out that these will be impacted even more than developed countries if such a 4°C warmer occurs.

2. Projected Effects of a 4°C Warmer World

Each of the chapters of the report deals with a different set of effects that having a 4°C world would have on various phenomena and processes. One of the important themes running through the report is that the effects would not be evenly distributed throughout the globe. You can see that many areas of the developed world would be hardest hit with regard to biodiversity, water resources, and heat extremes.

Phenomenon Effect in 4°C world Comments
1. CO2 Concentration and Ocean Acidification 390 ppm → 800 ppm, ocean 150% more acidic At 450 ppm, coral reef growth slowdown; coral reefs dissolve at 550 ppm
2. Droughts and Precipitation 20-30% more precipitation in winter; droughts more extensive in summer Extreme drought areas include: Amazon, western US, Mediterranean, southern Africa, southern Australia
3. Tropical Cyclones 2X current economic damage due to storms Most severe storms: NA, East Asia, Caribbean, Central America
4. Sea-Level Rises Sea level rises 1 meter Sea level could rise 2 meters if ice sheets melt in Greenland and Antarctica
5. Heat Extremes Some regions could be higher than 4°C, up to 10°C Areas of 6°C: Mediterranean, N. Africa, Middle East, US
Areas of 10°C: Arctic region
6. Agriculture Global food production will decrease Mid- to high-latitudes will see increase, low latitudes will see decrease; CO2 fertilization effect somewhat offsets yield reductions
7. Water Resources Population living in water scarce area 28% (current) → 43-50% Areas most effected: N. and E. Africa, South Asia
8. Ecosystems and Biodiversity 20-30% plant and animal species at risk of extinction Tropical and sub-tropical regions in Africa and S. America are particularly vulnerable
9. Human Health Increase in starvation, deaths due to weather extremes, increased disease transmission Disease-related deaths can be mitigated somewhat, but starvation and weather-related deaths are more difficult to mitigate
10. Non-linear effects Amazon Rainforest die-back, ice sheets melting, loss of coral reefs, expansion of ocean “dead zones”, Combination of non-linear effects causes crop yields to decrease 63-82%.

3. Strategy for Mitigation

Well, with the unending list of “gloom and doom” scenarios laid out above, the report itself does not lay out strategies for increased efforts to mitigate these effects by reducing greenhouse gas emissions. However, the comments on the report at the World Bank site do indicate the following components of such a mitigation strategy which are outlined below.

  • Support climate actions in country-led development processes;
  • Mobilize additional concessional and innovative finance;
  • Facilitate the development of market-based financing mechanisms;
  • Leverage private sector resources;
  • Support accelerated development and deployment of new technologies; and
  • Step up policy research, knowledge, and capacity building.

One of the biggest arguments against increased measures to mitigate greenhouse gas emissions is that it would cost resources that the world cannot afford in a time of a global economic slowdown. The point the World Bank makes is that inaction would cost us all a lot more.

Combining the approaches listed above will have the best chance to mitigate the current global warming trend so that it does not exceed 2°C, which would not cause us to live in a paradise here on this planet, but would at least avoid the “hell on Earth” scenario outlined in this report. A technological fix may not be possible, but a portfolio of solutions could spread the costs more equitably and more efficiently and thus reduce the economic impact they would have in the short run. If we don’t do anything at all, well, there won’t BE a long run.

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