The target has been set — a worldwide agreement to limit greenhouse-gas emissions by 2030 to a level that will hold global warming to no more than 2oC above the pre-industrial era. Representatives of the world's 196 nations will gather in Paris at the end of this month for the 21st meeting of the Conference of the Parties to the United Nations Framework Convention on Climate Change (COP21) to thrash out how it might be done.
The history of climate-change treaties suggests little ground for optimism. From Rio de Janeiro in 1992 to Kyoto in 1997 and Copenhagen in 2009, talks have tended to finish with fine words but no agreement and little action. Emerging economies blamed the developed nations for creating the problem in the first place, and not doing enough to help them transition to greener energy sources. Developed nations justified their failure to respond by pointing to the dirty coal plants springing up all over Asia. How could cutting their emissions offset that?
And looming over all was a huge fossil-fuel industry with no interest in the climate-change agenda and pockets deep enough to fund resistance.
Yet there are grounds to believe that the Paris talks could be the most productive yet. For a start, the political will to take meaningful action is in far greater supply than ever before, exemplified by the fact the world's biggest emitters, the US and China, look fully on board this time. And when public figures as diverse as Pope Francis and Mark Carney, the governor of the Bank of England, start talking about climate change in catastrophic terms, spiritual and financial, then it is clear the debate is leaving the deniers marginalised.
Second, the negotiators have learned from previous painful experience and have adopted a bottom-up approach. Countries have been charged to come up with their own plans, tailored to their own priorities and requirements, rather than be dictated to from above about what they should do, and how they should do it.
Third, and perhaps most important, has been the pace of development in renewable-energy generation technology, particularly wind and solar PV. And, as the technology has improved, the costs have come down steadily, which is not something that can be said of oil, gas, or nuclear. At the end of 2009, the year of the Copenhagen climate-change conference, there was a little over 150GW of installed wind-power capacity worldwide, and about 30GW of solar PV. The delegates to the Paris conference inhabit a world with well over 400GW of wind and around 230GW of solar PV. Unlike carbon capture and storage (CCS) technology, wind and solar PV are well-proven and cost-competitive.
The individual countries' plans come in the form of intended nationally determined contributions (INDC), which were all supposed to be submitted by the start of October. In fact, only 146 of the planet's 196 nation states met the deadline, but they account for 90% of global emissions. Their proposals, if fully implemented, would hold warming to 2.7oC, according to Climate Action Tracker (CAT), the independent scientific analysis produced by four research organisations that has been tracking climate action since 2009. This falls some way short of the 2oC target but establishes a reasonable benchmark to drive ambitions when the negotiations start in earnest. And there is plenty of scope for improvements in the INDCs of a number of countries, with CAT singling out Canada, Australia, New Zealand, Russia and Japan for having weak targets.
One drawback of the bottom-up approach has been the huge disparity of the INDCs - with different countries using different baselines and timelines for their proposed actions, and explaining how they intend to go about it in greater or (more usually) lesser detail. It makes them impossible to compare. Some countries have used a "business as usual" (BAU) baseline for emissions reductions, which means that emissions will continue to rise as their economies grow, but by less than they would without the mitigating action. Other states, the US for example, have set the emissions level of 2005 as their baseline, pledging to reach 26-28% below that level by 2025. The EU is using 1990 for its baseline, but is aiming to cut that by 40% by 2030.
The EU faces the further complication that its relatively ambitious target still has to be cut up and distributed among its 28 member states. That promises to be a mini-Paris summit in itself.
Paying for change
Finance is likely to be one of the conference's most contentious issues, as it was in Copenhagen. In Denmark, it was agreed that the rich countries would supply $30 billion of "fast-start" financial assistance to the poor countries, and that by 2020 it would be mobilising at least $100 billion a year. Which countries will contribute to that fund, and by how much, has still not been decided. However, as OECD secretary general Jose Angel Gurria recently pointed out, governments around the world are currently spending twice that much every year subsidising fossil fuels.
Another sticking point could be how progress against these various targets will be measured and monitored. The VW diesel emissions scandal, which broke last month and rocked the automotive industry, has destroyed confidence in self-regulation. But there's no mechanism yet in place to ensure promises are being kept, or to impose penalties for failure.
Intended nationally determind contributiions — How big emitters plan to clean up
China: Aims to reduce carbon intensity (CO2 emission per unit of GDP) by 60-65% below 2005 levels, with emissions peaking no later than 2030, increasing renewables share of energy generation to 20%. Wind power is forecast to grow from current installed capacity of 130GW to 250GW by 2020, and to continue growing at a rate of at least 20GW a year thereafter.
US: Aims to cut emissions by 26-28% below 2005 levels by 2025. No target given for wind specifically, but has targeted raising non-hydro renewables from current share of 12% of electricity generation to 20% by 2030.
EU: Pledges to cut emissions by 40% below 2005 levels by 2030. Has set no targets for renewables in general or wind in particular, but the European Wind Energy Association's (EWEA) central scenario envisages installed capacity rising from the current 142GW to 320GW. The low scenario, probably more realistic, aims for 250GW by 2030.
India: Aims to reduce carbon intensity by 33-35% below 2005 levels by 2030 and to achieve 40% of its electricity generating capacity from non-fossil fuel sources. Envisages rapid growth for wind - from today's 25GW of installed capacity to 60GW by 2022, and even faster expansion in solar - from 4GW now to 100GW by 2022, but calls for significant outside investment.
Canada: INDC aims for a 30% cut in greenhouse gas (GHG) emissions on 2005 levels by 2030, but gives little detail on how it will be achieved except by the inclusion of emissions removal through human-induced land use, land-use change and forestry (LULUCF). Climate Action Tracker (CAT) rates the INDC as "inadequate" and warns that Canada will miss its 2030 target by a wide margin. Best hopes for progress lie in the election of a more pro-renewable government.
Brazil: Aims to cut GHG emissions by 37% below 2005 levels by 2025, and by 43% by 2030. Key to this is restoring 120,000 square kilometres of forest, and eliminating illegal deforestation by 2030. No specific target has been set for wind, but the INDC calls for non-hydro renewables to generate 23% of the country's electricity by 2030. It currently stands at less than 10% with installed wind capacity of more than 7GW.
Russia: INDC aims to cut GHG emissions by up to 30% on 1990 levels by 2030, but the target is subject to "the maximum possible account of absorbing capacity of forests". CAT rates Russia's INDC as inadequate, while Thomas Hale, an associate professor at Oxford University's Blavatnik School of Government, describes it as "a magnum opus of hypotheticals".
Japan: The headline pledge is an emissions reduction target of 26% below 2013 levels by 2030, which is equivalent to 18% below 1990 levels. Another INDC rated as "inadequate" by CAT, which argues that with the policies it already has in place, the country could almost reach its target without taking any further action. Plan calls for renewables share of electricity generation to rise from its current level of 10% (mostly hydro) to 22-24% by 2030.
Australia: Aims to cut GHG emissions by 26-28% from 2005 levels by 2030 if LULUCF is taken fully into account, but provides little indication of how this might be achieved. According to CAT, "Australia stands out as having the largest relative gap between current policy projections for 2030 and the INDC target". New prime minister Malcolm Turnbull is seen as more pro-renewables than predecessor Tony Abbott.
Turkey: Plans a 21% reduction in GHG emissions from the BAU (business as usual) level by 2030, but will need international financial support. INDC envisages installed wind capacity to rise from current level of 4.46GW to 16GW by 2030, well below the 20GW by 2023 target set by the country's renewable energy action plan in February.
South Africa: INDC sets goals for an absolute peak, plateau and decline in GHG emissions that doesn't envisage them falling until 2035. CAT estimates that excluding LULUCF, South Africa's emissions in 2030 could be up to 82% higher than 1990 levels, and rates the plan inadequate. A 16.8GW target for renewables, split equally between wind and solar PV, has been set for 2030.
Indonesia: One of the world's biggest GHG emitters, primarily due to deforestation, peatland degradation and forest fires rather than fossil-fuel use. The INDC pledges to cut emissions by 29% by 2030, although it is unclear what baseline year is being used. The main plan of action is to triple its geothermal power, and to generate 17% of its energy from renewables with wind and solar PV accounting for 5% between them. The country's first wind project is scheduled for completion in 2019.
South Korea: INDC target to reduce GHG emissions by 37% from the BAU level by 2030 is another that gets CAT's "inadequate" rating. The country aims to reduce coal's share of energy generation from the current level of 45% to 32% by 2030, but nuclear power is expected to take up most of the slack. Modest growth in renewables is planned, but mainly in small wind and domestic solar.
New Zealand: "Creative accounting" is CAT's reaction to the proposals set out in New Zealand's INDC, which sets a target of a 30% cut in GHG emissions on 2005 levels by 2030. Again, extensive use of LULUCF measures are assumed for the country to meet its target. CAT calculates that if these are excluded, GHG emissions could be up to 32% above 1990 levels by 2030. The INDC makes no commitment to increasing renewables' share of energy generation.
Mexico: The INDC, one of the first to be submitted, sets an unconditional target of a 22% cut in GHG emissions below baseline by 2030, and a conditional target (based on technological and financial assistance) of 36%. There's a certain amount of confusion over what the baseline year is, but the country expects emissions to continue to rise, not peaking until 2025.