The IPCC Mitigation Report

Meher Engineer

IPCC's Working Group 3 (WG3) has released its report, on mitigation, meaning the actions needed to slow down climate change. The new report is more hopeful than the Working Group 2's report on adaptation, which described how Global Warming will make hunger, thirst, disease, refugees and war worse, in terrifying detail. The five terrors would fall on the poor, mostly those living in Asia, Africa and Latin America.

The most hopeful things in the WG3 report say that:
*    Limiting the increase in Global Mean Surface Temperature to within 2°C (3.6°F) of its pre-industrial level will not cost much, provided the necessary actions are started immediately and executed strongly. The actions will lessen the global economy's "consumption growth", which is expected to be 1.6%—3% per year over the coming decades, by a mere 0.06%.
Recalling what the world's governments said at Cancun in 2010—warming beyond 2°C was "dangerous"—the report adds that:
*    Greenhouse gas emissions grew at 2.2% per year during 2000-2010. CO2 accounted for about 76% of those emissions; 16% came from methane, 6.2% from nitrous oxide (N2O) and 2.0% from the fluorinated hydrocarbons, used in refrigerators for example. Annually, since 1970, about 25% of anthropogenic GHG emissions have been in the form of non-CO2 gases.
*   Only 10 countries produced about 70% of the world's CO2 emissions in 2010, from fossil fuels and industrial processes.
*    About half the cumulative human-caused CO2 emissions between 1750 and 2010 has happened over the last 40 years.
Large and rapid cuts in greenhouse gas emissions are, therefore, a must if "dangerous" warming is to be avoided. To avoid the danger:
*   The share of zero and low carbon energy sources—solar, wind, nuclear, fossil fuel with Carbon Capture and Storage (CCS)—to be at least tripled by 2050;
*    Greenhouse gas emissions to fall by 40-70% compared to their 2010 levels, by 2050;
*   CO2 emissions to fall to near zero by 2100.

Doing all that, requires humanity to spend about US $30 billion less per year on fossil fuels between 2010 and 2029; US $147 billion more per year on zero and low carbon energy sources; and, finally, several hundred billion US dollars more per year on improving energy efficiency. The amounts are tiny compared to the $ 500 billion that the USA spends every year on defence and to the current, annual global total investment in the energy system of US $1.2 trillion. Do less, the report says, and the promise of keeping Global Warming below 2°C, will not be kept, even though a 3°C rise might be avoided. Delay mitigation to 2030, and the 2°C limit will be crossed.

Keeping the temperature rise below 2°C has important co-benefits:
1)    Air pollution will fall. The World Health Organization reported in 2012 that about 7 million people died- one in eight of total global deaths -as a result of exposure to polluted air.
2)   Energy security, meaning less price volatility and fewer supply disruptions, will increase.
3)   The environment will be better protected.

Furthermore, the opportunity exists, over the next few decades, of building low-emission cities. Urban land cover is projected to expand by 56-310% between 2000 and 2030. Since most of the required infrastructure hasn't been built as yet, a tremendous opportunity exists to build new urban areas that emit fewer greenhouse gases. Seizing the opportunity requires strong policy, technical, financial and institutional measures.

The "energy intensity" of the global economy fell during 2000-2010: humans do produce goods in ways that are more energy efficient. Nevertheless, the Report adds:
"Without additional efforts to reduce GHG emissions beyond those in place today, emissions growth is expected to persist, driven by growth in global population and economic activities."
Between the economy and population, while the contribution from population growth between 2000 and 2010 remained roughly what it had been over the previous three decades, the contribution from economic growth rose sharply.
It follows that the planet will warm by about 4°C by 2100 compared to pre-industrial levels, unless additional measures to slow down human-caused climate change are made. The temperature difference between today's climate and that of the previous Ice Age was also 4°C. That shows how big the effect of human GHG emissions is likely to be, unless mitigation is done with fast and with a will.

Greenhouse gas emissions from deforestation are decreasing, because the rate of deforestation has been decreasing. GHG emissions, stemming from the human uses of land in agriculture, forestry etc. are decreasing; they now account for 24% of all human emissions. These emissions are expected to keep falling and might even go to zero by 2100.

Renewable energy is growing fast, but must be subsidised in order to grow more rapidly. Indirect subsidies mean taxing fossil fuels or adopting a cap and trade system. The report doesn't recommend any particular policy actions. It simply notes that "to help reduce possible adverse effects on lower income groups who often spend a large fraction of their income on energy services, many governments have utilized lump-sum cash transfers or other mechanisms targeted on the poor."

Vol. 46, No. 46, May25 -31, 2014