UN issues warming warning
There is a glaring and growing gap between global warming targets and reality.
A report by the science advisory group of the UN's Climate Action Summit 2019 says global temperatures since 2015 are on track to be the hottest on record for any five-year period.
However, current global commitments to cut greenhouse gas emissions will likely lead to a global temperature rise of between 2.9°C and 3.4°C by the end of the century, the report finds.
To actually limit warming to 2°C, countries will need to commit to emissions reductions that are triple their current commitments.
If the world is to limit warming to 1.5°C, those commitments need to be five times greater.
But the experts say it is not too late. It is technically still feasible to bridge this gap, but global ambitions must be increased urgently and backed up by immediate action.
It calls for fundamental socio-economic transformation in key sectors such as land use and energy.
The report aims to present a “transparent envelope” of authoritative and actionable cutting-edge science.
Levels of the main long-lived greenhouse gases, carbon dioxide (CO2), methane (CH4)) and nitrous oxide (N2O) have reached new highs.
The last time Earth’s atmosphere contained 400 parts per million CO2 was about 3-5 million years ago, when global mean surface temperatures were 2-3°C warmer than today, ice sheets in Greenland and West Antarctica melted, parts of East Antarctica ice had retreated, all causing global see level rise of 10-20m compared with today.
In 2018, global CO2 concentration was 407.8 parts per million (ppm), 2.2 ppm higher than 2017. Preliminary data from a subset of greenhouse gas monitoring sites for 2019 indicate that CO2 concentrations are on track to reach or even exceed 410 parts per million (ppm) by the end of 2019.
The report assesses the latest scientific studies on current and estimated future greenhouse gas emissions; they compare these with the emission levels permissible for the world to progress on a least-cost pathway to achieve the goals of the Paris Agreement.
This difference between “where we are likely to be and where we need to be” is known as the emissions gap.
Global emissions are not estimated to peak by 2030, let alone by 2020, if current climate policies and ambition levels of the Nationally Determined Contributions (NDCs) are maintained.
Preliminary findings from the Emissions Gap Report 2019 indicate that greenhouse gas emissions continued to rise in 2018.
The evidence continues to reinforce human influence as the dominant cause of changes to the Earth system, in a new geological epoch, the Anthropocene.
Growing climate impacts increase the risks of crossing critical tipping points.
These refer to thresholds that, if crossed, lead to far-reaching, in some cases abrupt and/or irreversible changes.