Over the first nine months of 2015, global mean warming reached 1°C above preindustrial for the first time, as reported by scientists from the Met Office and the Climate Research Unit at the University of East Anglia.

2015 is likely to become the warmest year in more than 11,000 years (see Figure 1). This signals a departure from the mild climate of the last 10,000 years in which agriculture and human civilisations have developed and thrived.

Given the lack of action in reducing emissions over the last decade, crossing 1°C warming is an inevitable, yet highly concerning event. It is a signal from the climate system that time is running out if we are to be able to reduce emissions fast enough to hold warming below 2°C and below 1.5°C by 2100.

Examples of climate impacts under a warming of 1°C experienced in 2015 include:

The third ever global coral bleaching event. Higher ocean temperatures, combined with ocean acidification, threaten coral reefs all over the world. A record El-Niño has intensified this bleaching event, and preliminary model projections indicate it’s likely to last well into 2016.
Record heat waves in India and Pakistan. The heat wave that hit India in May this year caused more than 2500 deaths, making it the fifth deadliest heat wave in history according to the Emergency Events Database EM-DAT. During this heat wave, and the following (but separate) heat wave that hit Pakistan in June (with about 2000 people dead), recorded temperatures were as high as 44-49°C.
A key part of the West Antarctica’s ice sheet, the Amundsen Sea region, has most likely been destabilised due to warming to date, and a recent modelling study indicates that this could destabilise the entire Western Antarctic, with resulting sea level rise of more than three metres over the next centuries.

Marcott 1deg — Figure 1: 2015 is likely to set a new record for being the warmest year in more than 11,000 years. Black lines indicate temperature as reported by Marcott et al., 2013 in Science, with uncertainties shown as shades. BP (before present) is meant relative to 1950. 2014 and 2015 values show the annual mean global temperatures based on the latest HadCRUT4 data set (Sept. ll 2015).

These observations add further support to one of the key messages of the UNFCCC Structured Expert Dialogue (SED) Report on the adequacy of the 2°C limit that:

Significant climate impacts are already occurring at the current level of global warming and additional magnitudes of warming will only increase the risk of severe, pervasive and irreversible impacts (See our Hot Topic and briefing note on further details on the outcomes of this report.)

While the technical and economic feasibility of holding below 2°C and limiting warming below 1.5°C by 2100 is not affected by crossing the 1°C level (see our briefing note on the feasibility of 2°C and 1.5°C), with each year’s delay in reducing global emissions, this task will get more difficult, and more costly.

The emission reduction commitments (INDCs) governments have put forward for COP21 in Paris, even if fully implemented, would put the world on track for a warming of 2.7°C (see Climate Action Tracker assessment).

Links to useful resources on this issue:

Hadley Centre temperature data
Blog on records in 2015

More global temperature data and figures:

NASA GISS Surface Temperature Analysis
Columbia University Global Temperature Maps
Columbia University Global Temperature — More Figures

Publications

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.

1.5°C-aligned 2030 and 2035 GHG emissions targets

We have produced factsheets for Australia, China, the EU, India, Indonesia and USA showing 2030 and 2035 greenhouse gas emission reduction milestones for each jurisdiction to align with the Paris Agreement’s 1.5°C goal – both including and excluding land use, land-use change and forestry.

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.

Climate Action Tracker: 2024 warming projection update

Despite an escalating climate crisis marked by unprecedented wildfires, storms, floods, and droughts, the Climate Action Tracker annual global temperature update shows global warming projections for 2100 are flatlining, with no improvement since 2021. The aggregate effect of current policies set the world on a path toward 2.7°C of warming.

Decarbonising light-duty vehicle road transport

The Climate Action Tracker provides updated 1.5ºC compatible benchmarks for the transport sector for the world as a whole and for seven individual countries; the US, EU, China, India, Brazil, South Africa and Indonesia.

Emissions Gap Report 2024: No more hot air … please!

The 2024 edition of UNEP’s Emissions Gap Report shows how much higher nations must aim. To get on a least-cost pathway for 1.5°C, emissions must fall 42 per cent by 2030, compared to 2019 levels. G20 nations, particularly the largest-emitting members, would need to do the heavy lifting.

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.

Methodology underpinning the State of Climate Action series: 2024 update

This technical note describes the State of Climate Action series’ methodology for identifying sectors that must transform, translating these transformations into global mitigation targets primarily for 2030, 2035 and 2050 and selecting indicators with datasets to monitor annual change. It also outlines the report’s approach for assessing progress made toward near-term targets and comparing trends over time.

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.

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Comment

Global warming reaches 1°C above preindustrial, warmest in more than 11,000 years