Global and regional impacts of climate change under Representative Concentration Pathways (RCPs) (B2b)

This report presents an assessment of global and regional impacts of climate change under six different levels of climate forcing and five plausible socio-economic scenarios which define population exposure to this change. Four of the climate forcings are based on Representative Concentration Pathways (RCPs), and produce median estimates of increase in temperature in 2100 above pre-industrial levels of 1.9°C (RCP2.6), 2.9°C (RCP4.5), 3.6°C (RCP6.0) and 5.3°C (RCP8.5). Two other new forcing pathways are used, leading to intermediate increases in temperature (median estimates 2.6°C and 4.2°C above pre-industrial levels). The five socioeconomic scenarios are taken from the Shared Socio-economic Pathways (SSPs) increasingly used in climate change assessments. Impact indicators are calculated using spatially-explicit global-scale impacts models representing impacts as a change in exposure to temperature extremes, the availability of water resources, river flooding, coastal flooding, drought and energy demands, in addition to impacts on crop suitability and ecosystems. Aggregate impacts are also expressed as a proportion of global GDP using the PAGE09 integrated climate-energy model.

 

The impact of shale gas on the cost and feasibility of meeting climate targets (C6)

In recent years, there has been considerable global and regional interest in shale gas, which it has been suggested could play a role as a bridging fuel to a low-carbon future, and which has led to a huge increase in indigenous gas production in the US. There remains, however, considerable uncertainty over shale gas resource availability and extraction costs, as well as the fugitive methane emissions associated with shale gas extraction.

This study considers the impact of a range of shale gas cost and availability assessments on mitigation scenarios aimed at achieving a limit to global warming of below 2°C in 2100, with a 50% likelihood. The study first discusses existing analysis and uncertainty around shale gas resource availability, extraction costs and fugitive methane emissions. It then describes how a global energy systems model (TIAM-Grantham) is used to examine the impacts of shale gas availability on global mitigation scenarios aimed at achieving a long-term temperature goal of below 2°C in 2100 (with 50% likelihood), the results of this analysis, which focuses on the global energy system costs, shale gas demand and primary energy usage impacts, and finally the implications of this analysis.

Report reviews

The first draft of this report was reviewed by two independent academics, to ensure analytical rigour and balance in the study. This first draft report, as well as the two reviews (which also include the report authors’ responses to them) are available below.

Low-carbon transition patterns in the BRICS countries – comparing global energy system models to national analysis (C5)

Hydro electric power plant in Brazil

Brazil, Russia, India, China and South Africa (BRICS) accounted for almost 40% of global energy-related CO2 emissions in 2012. Since 2000, these emissions have increased in all of these five countries. For China and India, the two biggest emitters, energy related CO2 emissions more than tripled and doubled, respectively, since 2000, driven largely by development (as defined through the metric of increased GDP per person), which has been offset to a limited extent by improvements in energy efficiency.

According to the IEA’s “current policies” scenario (which does not take into account Paris pledges), the BRICS countries could account for almost half of global energy-related CO2 emissions by 2040, with India and China alone responsible for 40% of the global total (more than 80% of the BRICS total). The feasibility of mitigating these emissions is therefore of central importance to the overall feasibility of avoiding dangerous levels of climate change.

The key question considered in this study is how for these regions a least-cost global mitigation pathway developed in the AVOID 2 programme, which achieves a below 2°C temperature change in 2100 (with 50% likelihood), the level of technological change compares to the maximum level of ambition proposed by these countries’ own analytical and policy groups, whether it be in long-term scenario analysis or nearer term policy and target proposals. The focus of this study is primarily on India and China, since, as well as their accounting for over 80% of current and future projected BRICS emissions, these regions are represented explicitly in the TIAM-Grantham energy systems model which is the central tool of analysis for the AVOID 2 decarbonisation feasibility analysis. The main sources of country-level analysis used to compare to the TIAM-Grantham outputs are: the UN’s Deep Decarbonisation Pathways project, which uses a range of country studies to assess the most rapid emissions reduction pathways possible; country 2050 energy/emissions calculators, whose most ambitious scenarios are used as a guide to what these countries’ analytical groups deem the maximum feasible level of technology deployment by 2050; and where available specific near-term (mostly to 2020) technology deployment targets stated in these countries’ own policy plans.

 

 

Implications for food security of large scale BECCS deployment (D2c)

Modern agriculture faces considerable challenges with many people currently lacking easy access to food or suffering malnourishment. Alleviation of this depends on food accessibility as well as availability. Global demand for crop production is rising driven by an increasing population, a shift in diet towards meat and dairy consumption and increasing biofuel consumption. Meeting this increasing future demand would require agricultural production to double by the 2050s.

Future emission pathways consistent with stabilising global temperatures below 2°C often require deployment of large-scale bio-energy and bio-energy carbon capture and storage (BECCS), as well as conserving terrestrial carbon stores  These requirements put pressure on land to be converted to grow biofuels or set aside for afforestation.

Producing food whilst adapting to and mitigating climate through deployment of bio-energy is a huge challenge, particularly when combined with a growing and developing population.

We present two modelled future agricultural land scenarios, in which the amount of agricultural land for food either remains stable over the 21st Century or declines. These scenarios are consistent with those requiring large-scale BECCS deployment, such as those that provide a greater than 50% chance of limiting warming to below 2°C in 2100.

Investigation of overshooting in the AVOID 2 INDC climate pathways (A3)

Recent developments in climate policy have led to the provision of a range of voluntary emission pledges from nations around the world (known as Intended Nationally Determined Contributions or INDCs) as part of the UNFCCC CoP process. These pledges are typically for emissions levels in year 2030 and there has been much consideration of the issue of whether they are compatible with a warming limit of 2°C or less.

Previous work has shown that achieving the UNFCCC’s long term climate goals might require there to be a so-called “overshoot” during the 21st century.

Earlier AVOID reports have looked at the concept of overshoot in a range of different emissions and climate pathways, reviewing current literature and performing some new analysis (AVOID 2 2015c). Overshoot is defined here as when one or more important climate metrics temporarily exceeds its long-term or 2100 value. Most focus has so far been on greenhouse gas concentration overshoots and global average temperature overshoots.

In this study we analyse a new set of emission and climate pathways developed to study the climate impacts of the recent international declared contributions to future mitigation (INDCs).