United in Science

The Paris climate agreement seeks to limit global warming to 1.5℃ this century. A new report, titled United in Science by the World Meteorological Organisation warns this limit may be exceeded by 2024 — and the risk is growing.

This first overshoot beyond 1.5℃ would be temporary, likely aided by a major climate anomaly such as an El Niño weather pattern. However, it casts new doubt on whether Earth’s climate can be permanently stabilised at 1.5℃ warming.

The report also found while greenhouse gas emissions declined slightly in 2020 due to the COVID-19 pandemic, they remained very high.

Concentrations of the three main greenhouse gases — carbon dioxide (CO₂), methane (CH₄) and nitrous oxide (N₂O), have all increased over the past decade. Current concentrations in the atmosphere are, respectively, 147 per cent, 259 per cent and 123 per cent of those present before the industrial era began in 1750.

Greenhouse Gas Concentrations in the Atmosphere – Global Atmosphere Watch

  • Concentrations of the major greenhouse gases, CO2, CH4, and N2O continued to increase in 2019 and 2020.
  • Overall emissions reductions in 2020 will lead to a small reduction in the annual increase of the atmospheric concentrations of long-lived greenhouse gases.
  • Sustained reductions in emissions are required to stabilize global warming.

Global Fossil CO2 Emissions – Global Carbon Project

  • Global fossil CO2 emissions reached a new record high of 36.7 Gigatonnes (Gt) in 2019, 62% higher than in 1990.
  • CO2 emissions will decline in 2020 due to confinement policies imposed in many countries. At their lowest point, in April, daily CO2 emissions were approximately at the level they were in 2006, and 2020 emissions overall are estimated to decline by 4% to 7% compared to 2019 levels.
  • Global CH4 emissions from human activities have continued to increase over the past decade. Current emissions of both CO2 and CH4 are not compatible with emissions pathways consistent with limiting global warming at 1.5 °C or well below 2 °C above pre-industrial levels, the goal of the Paris Agreement.

Global Climate in 2016–2020 – WMO

  • The 5-year period from 2016–2020 is expected to be the warmest on record with an average global mean surface temperature of 1.1 °C above pre-industrial era (1850–1900).
  • Arctic sea-ice continues its long-term downward trend. Global mean sea-level has been rising faster than the long-term trend. A greater loss of ice mass from the ice sheets contributed to an increased sea-level rise.
  • Major impacts have been caused by extreme weather and climate events. A clear fingerprint of human-induced climate change has been identified on many of these extreme events.

The Ocean and Cryosphere in a Changing Climate – Intergovernmental Panel on Climate Change

  • Human-induced climate change is affecting life-sustaining systems, from the top of the mountains to the depths of the oceans, leading to accelerating sea-level rise, with cascading effects for ecosystems and human security.
  • Impacts from climate-related changes in the ocean and cryosphere increasingly challenge efforts to develop and implement adaptation and integrated risk management responses.

Water and Cryosphere – WMO

  • Water is a key commodity that sustains livelihoods – water shortages for human consumption, food production and energy supply are major roadblocks for the Sustainable Development Agenda.
  • Water is a threat – floods and droughts produce the most severe impacts of all disasters worldwide.
  • Water is key for adaptation – climate change impacts are most felt through changing hydrological conditions including changes in snow and ice dynamics.

Global Climate in 2020–2024 – WMO Global Annual to Decadal Climate Update

  • There is a growing chance of annual global mean near surface temperature temporarily exceeding 1.5 °C above the 1850–1900 pre-industrial level, being ~20% in the 5-year period ending in 2024.
  • There is a high risk of unusual regional rainfall over the period, with some regions experiencing increasing droughtrelated risks and others increased risks associated with heavy rainfall.
  • Within the next 5 years, the Arctic is predicted to continue to warm at more than twice the overall global rate

Emissions Gap – UN Environment Programme

  • The Emissions Gap in 2030 is estimated at 12-15 Gigatonnes (Gt) CO2e to limit global warming to below 2°C above pre-industrial levels by the end of this century. For the aspirational 1.5 °C goal, the gap is estimated at 29-32 GtCO2e, roughly equivalent to the combined emissions of the six largest emitters.
  • It is still possible to bridge the Emissions Gap – but this will require urgent and concerted action by all countries and across all sectors.
  • Looking beyond the 2030 timeframe, new technological solutions and gradual change in consumption patterns are needed at all levels. Transformational action can no longer be postponed.

Earth System Observations during COVID-19 – UNESCO-IOC and WMO

  • The COVID-19 pandemic caused significant impacts on land-based, marine and air observing systems, which is affecting the quality of forecasts and climate services.
  • The pandemic demonstrated the vulnerability of components of the global observing system for weather, water, climate and environment and the need for investment to address this; it also demonstrated the resilience of a system-of-systems approach.
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