On 23 September 2019, the World Meteorological Organization (WMO) published a report on The Global Climate in 2015-2019 to inform the United Nations Secretary-General’s Climate Action Summit due to be held on the same day in New York. The report says that the global average temperature has increased by 1.1°C since the pre-industrial period, and by 0.2°C compared to 2011-2015.
“Climate change causes and impacts are increasing rather than slowing down,” said WMO Secretary-General Petteri Taalas, who is co-chair of the Science Advisory Group of the UN Climate Summit. “Sea level rise has accelerated and we are concerned that an abrupt decline in the Antarctic and Greenland ice sheets, which will exacerbate future rise. As we have seen this year with tragic effect in the Bahamas and Mozambique, sea level rise and intense tropical storms led to humanitarian and economic catastrophes
“The challenges are immense. Besides mitigation of climate change, there is a growing need to adapt. According to the recent Global Adaptation Commission report the most powerful way to adapt is to invest in early warning services, and pay special attention to impact-based forecasts. It is highly important that we reduce greenhouse gas emissions, notably from energy production, industry and transport. This is critical if we are to mitigate climate change and meet the targets set out in the Paris Agreement.
“To stop a global temperature increase of more than 2 degrees Celsius above pre-industrial levels, the level of ambition needs to be tripled. And to limit the increase to 1.5 degrees, it needs to be multiplied by five,” he said.
The climate statement – which covers until July 2019 – provides a unified assessment of the state of Earth system under the increasing influence of climate change, the response of humanity this far and projected changes of global climate in the future. It highlights the urgency and the potential of ambitious climate action in order to limit potentially irreversible impacts.
An accompanying WMO report on greenhouse gas concentrations shows that 2015-2019 has seen a continued increase in carbon dioxide (CO2) levels and other key greenhouse gases in the atmosphere to new records, with CO2 growth rates nearly 20% higher than the previous five years. CO2 remains in the atmosphere for centuries and in the ocean for even longer. Preliminary data from a subset of greenhouse gas observational sites for 2019 indicate that CO2 global concentrations are on track to reach or even exceed 410 ppm by the end of 2019.