RESEARCH ARTICLES CURRENT SCIENCE, VOL. 122, NO. 6, 25 MARCH 2022 689 *For correspondence. (e-mail: tejalk@nias.res.in) A methodology to correlate short-term regional climate action and long-term global temperature goals Tejal Kanitkar 1, * and Haritha Songola 2 1 Energy Environment Programme, National Institute of Advanced Studies, Indian Institute of Science Campus, Bengaluru 560 012, India 2 Tricontinental Institute of Social Research, New Delhi 110 016, India We provide a methodology for assessing short-term mitigation targets for a region against long-term global goals of addressing climate change. We first estimate the per capita fair share of the remaining carbon budget for India from 2018 onwards. Potential long- term emissions trajectories between 2018 and 2100 compatible with this fair share are then constructed. These budget-compatible trajectories are then com- pared to the Nationally Determined Contribution (NDC) as well as results from five modelling studies for India. The methodology discussed here can be used to assess the adequacy of NDCs and also helps in rationalizing the process of target setting for climate action. Keywords: Carbon budget, climate change, emissions trajectories, fair share, global temperature. AS part of its Nationally Determined Contributions (NDCs) under the Paris Agreement, India has set three quantita- tive targets for the year 2030. It has committed to reduc- ing its emissions intensity by 33%–35% of 2005 levels, increasing the share of non-fossil fuel-based energy sources in its cumulative electric power installed capacity to 40% ‘with the help of transfer of technology and low-cost in- ternational finance including from green climate fund (GCF)’, and to create an additional carbon sink of 2.5–3 billion tonnes of CO 2 equivalent through more forest and tree cover 1 . These targets are likely to be revised as the Prime Minister of India, at the 26th Conference of Parties in Glasgow in 2021 (COP-26), has declared enhanced miti- gation contributions from the country by 2030. However, at the time of writing this article, these political declarations at the World Leaders’ Summit during COP-26 have yet to be communicated in written form either in a policy docu- ment from the Government of India (GoI) or as enhanced NDCs to the United Nations Framework Convention on Climate Change (UNFCCC). We will restrict the analysis in this article therefore to the original NDCs submitted by India to UNFCCC in 2015. The NDCs, since they were announced, have been the subject of much debate in the country and internationally. India’s NDCs have been pronounced to be good, low ambition, or just right by various reports. The Emissions Gap Report for 2018 published by the United Nations Environmental Program (UNEP), declares that India’s emissions with its current policies, will be 10% below what it has committed to reduce, making its actual achieve- ments better than its NDCs 2 . Mohan and Wehnert 3 expli- citly argue that while India is well on track to meet its targets, this may be because targets themselves are fairly modest. Various other individual and synthesized assess- ments of India’s and other countries’ NDCs can be found in the literature 4–7 . However, one should remember that most NDCs, including India’s, encompass a time horizon going up to 2030 only. On the other hand, global mitiga- tion targets, be they temperature or emissions, are arrived at by running climate models for much longer time periods and typically cover a much broader time horizon, at least up to 2100. While earth system models and general circulation models have much longer timelines, even among the 19 integrated assessment models considered by the Intergovernmental Panel on Climate Change (IPCC) for the special report on 1.5°C global warming (SR1.5), nine have a time horizon extending to 2100, five extending beyond 2100, and only five have a time horizon of up to 2050 or 2060. On the other hand, regional models typically built for specific nations or economically integrated regions use more de- tailed socio-economic variables and assumptions and therefore, restrict their time horizons to smaller time periods. Examples for India include the five models commissioned by the Ministry of Environment and Forests in 2010, GoI (ref. 8). The NDCs that nations then declare often are or can be based on assessments of these models built for shorter time horizons. An assessment of whether such targets are compatible with long-term cli- mate goals requires some extrapolation. In this study, we use the carbon budgets approach to arrive at an estimate of a fair share of the global carbon budget for each country/region. Our analysis includes both the 1.5°C and 2°C temperature targets. We do not claim that a particular estimate of fair share arrived at in this