PLEA Network

10 November 2023, James Hansen et el: How We Know that Global Warming is Accelerating and that the Goal of the Paris Agreement is Dead. Delayed response of climate makes human-made climate change a grave threat, especially  for young people. Governments will not make required changes to energy policies based on theoretical threats – there must be sufficient empirical evidence of harm to force action. Thus, delayed response makes it difficult to avoid near-term, growing, climate impacts, but it does not prevent achievement of policies that will lead to a hospitable climate with a bright future for young people. Time is running short, however, and effective actions at this point require a good understanding of ongoing climate change and the responsible mechanisms. The proximate cause of ongoing global warming is Earth’s energy imbalance (EEI). Earth is now absorbing more energy incoming from the Sun than the planet is sending back to space as reflected solar light and emitted thermal (heat) radiation. As long as that imbalance is positive – more energy coming in than going out – Earth will continue to get hotter. Factors that alter Earth’s energy balance are called climate forcings. There are two large human-made climate forcings: changes of atmospheric greenhouse gases (GHGs) and changes of aerosols. GHGs reduce heat radiation to space; thus, an increase of GHGs causes a positive energy imbalance, more energy coming in than going out, which causes warming. Aerosols reflect sunlight to space, which is a negative contribution to EEI that causes cooling. Read more here