I write to respond to recent opinions regarding climate. I am a scientist with colleagues at Harvard-Smithsonian Center for Astrophysics (CfA), where I have previously given an invited seminar. I was also a member of the Miller Institute for Basic Research in Science at UC Berkeley, where I interacted with climate science experts in the Department of Earth and Planetary Science. I share the following clarifications regarding climate science:
- While the human contribution of greenhouse gases (carbon dioxide, methane, etc.) to the atmosphere is insignificant to past levels in geologic history (4.5 billion years), the recent (post-1880) rate of change is significant and unprecedented in Earth’s history.
- A growing body of evidence clearly indicates that irreversible changes to global ecosystems are occurring due to the increase in greenhouse gases. This has triggered, for example, the warming of oceans and the consequent bleaching and death of coral reefs.
- The full impact of past greenhouse gas emissions has yet to be felt because of a thermal time constant. For example, the longest day of the year
- is in June, yet the highest temperatures of summer are delayed until July and August.
- Humans have already demonstrated that small changes in atmospheric content can have big impacts. For example, the release of chlorofluorocarbons (CFCs) previously used in refrigerants led to thinning of the ozone layer over the poles and even New England. A scientific, government, and industrial partnership averted this crisis by finding an alternative but cost-effective refrigerant. An equivalent solution for greenhouse gas emissions presents a more significant technical and social challenge.
- I stress that science is not consensus driven, it is evidence driven. Skepticism is part of the scientific process and allows scientists to determine the clearest connections within and between complex systems. As humans, there are things that we may want to be true, but wishing does not make them so. The rigorous process of science helps us identify those things that are true and provides us with the evidence to explain why. Extraordinary claims require extraordinary evidence; hearsay and opinion fall short of this bar.
Justin Brown
Park Lane
