Robert W. Corell (American, born 1934), PhD, is an oceanographer and engineer who is actively engaged in research on global change and public policy. He formerly taught at universities in the United States and Norway and is now principal of the Global Environment and Technology Foundation in Arlington, Virginia.
In June 1992 heads of state from 108 nations, delegations from 172 countries, and 2,400 nongovernmental organizations gathered in Rio de Janeiro for the first “Earth Summit.” They established the historic UN Framework Convention on Climate Change (UNFCCC) —a formal international treaty that went into full force in March 1994. It is the treaty within which international climate negotiations and protocols take place—involving the 194 nations that have ratified the convention. The UNFCCC sets forth a framework for addressing climate change, and its central goal is stabilization of greenhouse gas concentrations in the atmosphere at a level that would prevent dangerous anthropogenic interference with the climate system. Such a level should be achieved within a time frame sufficient to allow ecosystems to adapt naturally to climate change, to ensure that food production is not threatened, and to enable economic development to proceed in a sustainable manner.
Since 1994, the UNFCCC has hosted sixteen Conferences of the Parties (COP) and succeeded in agreeing on a number of protocols, like the Kyoto protocol, and other formal agreements. The most recent were COP 15 in Copenhagen, Denmark, in 2009, COP 16 in Cancun, Mexico, in 2010, and COP 17 in Durban, South Africa, at the end of 2011.
The objective of the COP meetings is to negotiate an agreement to reduce global greenhouse gas emissions. As part of the negotiations, the 194 participating nations have periodically made public their current goals for emissions reductions and related climate change actions. These 194 publicly available goals are tracked by a number of organizations and provide a possible starting point if one wants to forecast future emissions and the resulting global climate change.
In the following I describe the consequences if the current 194 national emissions-reduction goals were implemented. This may well describe the climate situation in 2052, although I hope not. I hope that the UNFCCC process will lead to much lower emissions in the next forty years, although the lack of recent progress makes this hard to believe.
Projections Based on IPCC’s Scenarios
There are a number of analytical computer-based tools for projecting the outcomes of different assumptions concerning climate gas emissions during the rest of this century. To bring some order to the plethora of forecasts, the UN Intergovernmental Panel on Climate Change (IPCC) in 2000 established a set of six standard scenarios for global socioeconomic-technological development to 2100.
IPCC uses these scenarios to estimate the future climate gas emissions in each scenario and provide assessment reports that reflect the current knowledge about the resulting climate change in each scenario. The latest assessment, published in 2007, concluded that the global average surface temperature is most likely to increase by 2.5°C by 2100 in the scenario with the lowest emissions (“B1”) and by 4.8°C in scenario with the highest emissions (“A1FI”)—all relative to the temperature in preindustrial times. The temperature increase by 2050 was estimated to be between 1.8°C and 2.2 °C. The current temperature is 0.7oC higher than in preindustrial times.
Projections Based on Current National Commitments
But instead of using the IPCC scenarios as a starting point, one can start from the 194 national emission reduction goals mentioned above and calculate the consequences if these goals were implemented. A central tool for doing this is a global climate simulation model called C-ROADS,20 which tracks the publicly available national pledges and uses them as input to the model. A C-ROADS projection made June 29, 2011, concluded that if all 194 nations live up to their proposed goals under the UNFCCC process, the global average surface temperature will increase by 2.2oC by 2050 and 4.1oC by 2100. The uncertainty in the projections is large (plus or minus a degree or so), but the conclusion from C-ROADS is that the sum of current national commitments leads to a future that is nearly as warm as the “worst” IPCC scenario (“A1FI”).
Our Recent Emissions Path and Future Implications
Of the six IPCC scenarios, A1FI is the one that projects the highest future emissions. Still, according to the Global Carbon Project, which annually reports carbon budgets and trends including global carbon emissions and atmospheric concentrations of global carbon, the path of actual climate gas emissions over the last decade is almost identical to the emissions projected in A1FI. Actual global emissions followed A1FI rather precisely from 2004 to 2009 but did deviate temporarily in 2010, most likely due to the global financial crisis of 2007 and 2008, and are generally expected to be back on the A1FI trend by 2015.
A1FI portrays a future with high economic growth, continued globalization, rapid technological change, and an increase in the global average surface temperature in 2050 by 2.4°C and in 2100 by 4.8°C. As mentioned, the sum of current national pledges—if implemented— will lead to a future that closely tracks A1FI, at least until 2050. Therefore, it is possible to use the detailed global projections from the IPCC Global Circulation Models22 database to make more detailed regional forecasts of the consequences of implementing the current national commitments. For example, the global pattern increase in average surface temperatures in 2050 for A1FI is shown in figure 2-5. We see substantial increases in the temperature over much of the Arctic (more than plus 4oC) and considerable increases over land (between plus 2oC and 4oC), while the oceans are projected to warm little (less than plus 2oC). Notice that these increases are for the next forty years only.
The implications of this pattern of temperature change are described in detail in the literature. The impacts are likely to be substantial. Projections state that many large-scale, terrestrial, and marine ecosystems will be unable to adapt to the rate of climate change. Water is likely to be a serious challenge, particularly for developing countries, with both availability and quality at risk, while precipitation changes are likely to increase droughts and, in other regions, floods.
Glaciers by 2052 are likely to be melting at increased rates. Sea levels will rise largely as a consequence of thermal expansion of the surface layers. The only good news seems to be that there will be higher crop yields in some high-latitude regions, like Scandinavia, Siberia, and Canada, while food yields may fall in the developing world.
By 2052, the additional projected average sea-level rise is upward of 0.3 meters. But small islands in the Asian Pacific region may experience three to five times this average. The projections suggest an increase in weather extremes and changes in regional microclimate, such as increased intensity of hurricanes, poleward movement of thunderstorms, and increased intensity of rain. Coastal regions are likely to be at risk, with sea-level rise in lowland regions, such as Bangladesh, displacing millions of people. Vector-borne and waterborne disease will increase, especially in regions with inadequate health-care systems.
So these are the consequences in 2052 if the world implements the current national proposals for greenhouse gas reductions made by the 194 nations of the UNFCCC.
However, there are serious and credible analyses that suggest that this will not be the course the world will take. These analyses suggest that technologies and sustainable energy resources are known or available today sufficient to perform the energy transition of the twenty-first century, and create a world in 2052 that is far brighter than that arising from implementation of current pledges.