3 October, 2018

Integrated Assessment Models: what are they and how do they arrive at their conclusions?

Authors

Bill Hare, Robert Brecha, Michiel Schaeffer

Bioenergy, like that produced from rapeseed, represents a key area of uncertainty in IAMs.

Integrated Assessment Models (IAMs) models are used to evaluate the technological and economic feasibility of climate goals such as the Paris Agreement’s long-term temperature goal to hold global warming well below 2˚C and pursue efforts to limit this warming to 1.5˚C above pre-industrial.

The results of these models are assessed in Intergovernmental Panel on Climate Change (IPCC) reports, and play a central role in the IPCC Special Report “Global Warming of 1.5°C” (SR1.5).

This briefing sets out some of the important context and caveats in relation to understanding IAMs and their results, particularly in relation to the Paris Agreement’s 1.5°C limit.

Publications

Reversal of the impact chain for actionable climate information

This study helps local decision-makers understand the link between the risks they want to avoid (i.e. health-related heat risks) and CO2 emissions using a new method that makes identifying critical risk levels easier for non-scientists.

Humid heat exceeds human tolerance limits and causes mass mortality

With critical physiological limits to human heat tolerance drawing ever closer, this Comment highlights the urgent need to limit further climate warming and emphasises the adaptation challenge ahead.

Spatially resolved emulated annual temperature projections for overshoot pathways

This study presents a new dataset of annual temperature projections for different overshoot pathways (when the 1.5 °C of global warming limit is exceeded). The data offers a unique opportunity to study local and regional climate change impacts of a range of overshoot scenarios, including when temperature thresholds might be exceeded, and by how much.

Geological Net Zero and the need for disaggregated accounting for carbon sinks

This study in Nature show that definitions of net zero now in widespread use will not actually stop global warming. The paper demonstrates that relying on natural carbon sinks, such as in forests or oceans, to 'offset' ongoing fossil fuel emissions will lead to continued warming.

The role of northern forests in limiting warming to 1.5°C

Northern forests are critical in the race to net zero CO₂ by mid-century. Protecting and restoring these forests, alongside steep and rapid reductions in fossil fuel emissions, is essential both to mitigating emissions and to supporting forest ecosystem services and biodiversity.

Rapid urbanisation and climate change key drivers of dramatic flood impacts in Nepal

New study finds the devastating floods in Nepal late September were exacerbated by rapid urbanisation and climate change. The analysis found the relentless rain, which fell on saturated ground in the late monsoon, was made at least 10% heavier and 70% more likely by climate change.

LNG shipbuilding industry heading to huge oversupply

The LNG shipbuilding industry appears to be doubling down on building new carriers, ignoring the global shift to a low carbon economy and putting itself into an even worse oversupply situation than a year ago, we find in our updated report.

Seasonal forecast of two-metre temperature and precipitation in Tanzania: A hybrid cluster and point-by-point machine learning approach

Seasonal forecasting of atmospheric parameters is important in various fields including agriculture. This study tests how machine learning can complement dynamic models using Tanzanian seasonal forecasts and finds this process uses far less computational power.

Overconfidence in climate overshoot

Even if it is possible to reverse the rise of global temperatures after a temporary overshoot of 1.5°C, some climate damages triggered at peak warming, including rising sea levels, will be irreversible, according to a new study published today in Nature.

Fracking the Kimberley: the Canning Basin development plans

We've calculated the climate implications of fracking the Canning basin, part of the remote and pristine Kimberley region in Western Australia. Four companies have their eyes on this region, home to the endangered bilby.

Solar geoengineering: a note to inform discussions on physical climate impacts, risks and governance issues

With international efforts on climate action still not on track to limit warming to 1.5°C, technological fixes that aim to intentionally alter the Earth’s climate, such as solar geoengineering, might seem like appealing options for tackling global warming. But they come with questions in terms of feasibility, impacts and risks, governance and geopolitics, and who may or may not benefit.

How can event attribution science underpin financial decisions on Loss and Damage?

With climate extremes hitting nations across the globe, disproportionately burdening vulnerable developing countries, funding for loss and damage is an acute need. Attribution science can provide useful information for decision makers.

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Decarbonisation targets and 1.5℃ pathways

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