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No mitigating action could lead to a 4m rise in sea level by 2300.

Without mitigating for climate change, sea level could rise by about a metre this century. This research investigated the potential sea-level rise that we could see if we are able to keep global temperature rise below 1·5°C or 2°C by the end of the century - finding sea-level rise could be kept below 46cm and 54cm respectively. Taking no mitigating actions to reduce emissions could lead to a 4m rise in sea level by 2300, a scenario that would see major consequences for populations and ecosystems in coastal and lower lying areas worldwide.

Cited in the IPCC special report for 1·5°C warming, the research was part of the 'Sea level rise trajectories by 2200 with warmings of 1·5 to 2 degree C project' led by Dr Svetlana Jevrejeva at the National Oceanography Centre, with co-investigators at the University of Oxford.

We have 17 years left before we exceed the carbon budget to keep below 1·5°C.

Using a new approach to make predictions, researchers have estimated the total carbon budget for keeping global temperatures below 1·5°C. Their research shows that, at the current carbon dioxide emission rates, there are 17 years left before we have used up all the allowable carbon dioxide (CO₂) emissions. This means that there is a very short window of time to develop the more carbon-efficient, and ultimately carbon-neutral, society needed to prevent warming above 1·5°C.

The project, 'Defining adjustable emission pathways to 1·5 degrees C warming, and assessing their feasibility, physical consequences and impacts', known as ADJUST 1·5, was led by Dr Phil Goodwin with co-investigators at the University of Southampton. Their research was cited in the IPCC special report for 1·5°C.

Current models have underestimated the uptake of CO₂ by the ocean.

The ocean naturally captures and stores CO₂ from the atmosphere, and this is factored into climate models. However, this research found evidence that, where we have been able to look, current models typically underestimate the recent and future increase in uptake of human-generated CO₂ by the ocean. Researchers are now working to eliminate biases in the models we use to understand the global carbon budgets in the coming decades and beyond.

'CURB CO₂: Carbon uptake revisited - Biases corrected using ocean observations' was led by Dr Paul Halloran with co-investigators at the University of Exeter.

Keeping warming below 1·5°C compared to 2°C is much better for biodiversity.

Limiting global warming to 1·5°C avoids half the risks associated with warming of 2°C for plants and animals, and two thirds of the risks to insects. Insects are particularly sensitive to climate change. At 2°C warming, 18% of insects studied are projected to lose more than half their geographical range, with the three major groups of insects responsible for pollination - vital to ensure global food security - shown to be especially sensitive to warming.

There is a significant benefit to keeping warming below 1·5°C compared to 2°C: in the former scenario, more species can keep up or even gain in range; if the latter, many species cannot keep up and far more species lose large parts of their range. Benefits occur everywhere but are greater in Southern Africa, the Amazon, Europe and Australia.

This research, 'Implications of the Paris agreement for biodiversity and conservation planning (IMPALA)', was led by Professor Rachel Warren at the University of East Anglia, and cited in the IPCC special report on 1·5°C warming.

Planting trees could be more effective than planting bioenergy crops.

The majority of scenarios showing we can limit warming to 1·5°C or 2°C are based on reducing CO₂ emissions as well as removing carbon from the atmosphere, often using an approach of planting bioenergy crops coupled with carbon capture and storage (BECCS). However, plants naturally take up CO₂ from the atmosphere and store it in biomass and soils, so increasing forest also results in CO₂ removal. This research found that increasing forest area and conserving current forests could be more effective than a large-scale commitment to BECCS in meeting the Paris climate agreements, and that this is especially true if land is deforested to make way for bioenergy crops, which results in an overall loss of carbon from the land.

'Climate, land-Use and ecosystem services at 1·5°C' was led by Professor Peter Cox of the University of Exeter, with Dr Anna Harper at the University of Exeter and co-investigators at the Centre of Ecology & Hydrology and the University of Bristol.

Thawing permafrost and natural wetlands can make it more difficult to limit global warming.

A warmer climate will trigger more natural emissions of CO₂ and methane from thawing permafrost and wetlands, on top of the emissions from burning of fossil fuels. These natural emissions have typically not been considered in previous assessments of the carbon budget. Taken in to account, allowable carbon emissions for limiting warming to 1·5°C are reduced by around 12%. This is equivalent to just over three years of human carbon emissions at 2017 emission rates. In the 2°C warming scenario, allowable carbon in reduced by 8·5%, equivalent to 4·4 years.

'Climate feedbacks from wetlands and permafrost thaw in a warming world (CLIFFTOP)' was led by Dr Garry Hayman at the NERC Centre of Ecology & Hydrology (CEH), with co-investigators at the CEH and the University of Leeds. Their research is cited in the IPCC special report on 1·5°C warming.

The remaining carbon budget is equivalent to less than 20 years of emissions at current levels.

In 2014, the IPCC made an assessment on the amount of CO₂ emitted globally that would cause warming of 1·5°C by the end of the century. This research has shown that the remaining carbon budget is likely to be significantly more than assessed at the time of IPCC 5th report. The research found biases in the previous models and, once corrected, estimated the remaining carbon budget for 1·5°C is about 200 gigatonnes of carbon, equivalent to less than 20 years of emissions at current levels.

'Quantifying the cumulative carbon emissions consistent with a 1·5°C global warming (TCRE1·5)' was led by Professor Pierre Friedlingstein at the University of Exeter, with co-investigators at the University of Oxford. Research from the project is cited in the IPCC special report on 1·5°C warming.

Methane reduction could play significant role in achieving 1·5°C target.

Methane is a more potent greenhouse gas than CO₂, so reducing methane emissions could make a substantial difference in our chances of meeting the Paris agreement targets by increasing the allowable carbon budget. Reducing methane emissions would also help lower concentrations of ozone gas in the atmosphere, which is harmful to plants, resulting in the vegetation being able to take more CO₂ out of the atmosphere. This research concluded that early mitigation of methane emissions would significantly increase our chances of stabilising global warming below 1·5°C, alongside other benefits to human health and biodiversity.

The 'Methane, ozone, and the carbon budget for 1·5°C (MOC1·5)' research was led by Professor Bill Collins at the University of Reading, with co-investigators at the University of Exeter, and was cited in the IPCC Special Report on 1·5°C warming.