Date: 30th July 2025

Time: 1:00pm – 1:45pm

Location: Online

Global average temperature has risen 1.2 degrees since pre-industrial times, exceeding the Medieval warming period, as shown by shown by extensive global records and natural and independent natural proxies. This warming cannot be explained by natural variation in Solar activity, orbital cycles, or “coming out of the last ice age”: it is primarily due to human-induced CO2 emissions.

For nearly 800,000 years CO2 naturally oscillated between 170 and 300 ppm but human activity has increased it 420 ppm and it is still rising. CO2 absorbs and re-emits infrared radiation, slowing the escape of heat energy from the troposphere into space, leading to a net warming of the planet. These heat trapping properties of CO2 have been known since the 1860s and the impact of increased atmospheric CO2 on the Earth’s incoming vs outgoing energy balance is directly measurable by satellites.

Nevertheless, under almost every online article or video about climate change there are comments which attempt to promote doubt by repeating long-debunked myths. The bad-faith actors posting the comments are often the victims of propaganda, have anti-science agendas related to political ideologies, or even financial incentives.

Thankfully, there are many resources available online to check information and better understand the full context of denier talking points, e.g. https://www.desmog.com / https://skepticalscience.com