Back at the end of October 2017, within the first year of starting this blog, I wrote a piece on how climate change deniers were trying to tell people that climate scientists are exaggerating the amount of sea-level rise. At that point, the rate of global mean sea-level (GMSL) rise was 3.3 +/- 0.4mm per annum and the trend was roughly linear1.
The person who used to be the stupidest member of parliament, Craig Kelly, was one of the worst offenders in this effort, initially stating that a photograph of Fort Denison, in Sydney Harbour, his only ‘data’, showed that sea-level had not risen since the late 1800s2. His next attempt was to pretend that sea-level was not a problem for Pacific islands because atolls floated on the ocean3. He then stated that sea-level rise was not a problem because climate change wasn’t happening4. It is hard to comprehend such stupidity.
GMSL has continued to rise and has reached a new record high for the data from satellite altimeter measurements which have been taken since 1993. During the first decade of such readings (1993-2002), the rate of GMSL rise was 2.27mm/yr. In the most recent decade (2013-2022), that rate has increased to 4.62mm/yr. So, the rate of GMSL increase is itself increasing. This sea-level rise has contributions from various sources. Over the interval from 2005 to 2019, land ice loss from glaciers and the ice sheets of Greenland and Antarctica contributed 36% to the GMSL rise, while thermal expansion (water expands when heated) contributed 55%. Variations in land water storage contributed 9%5.
So, the rate of sea-level rise is increasing, and it is doubtful that this rise can be stopped. This is because the amount of carbon dioxide currently in the atmosphere has already guaranteed an average global temperature rise well over 2°C6, that will cause more thermal expansion of ocean water. In addition, the rate of ice loss from the Greenland and Antarctic ice sheets is increasing. In the period from 1992 to 1996 these ice sheets lost an average of 105 gigatonnes of ice per annum (i.e. 105 billion tonnes per year), whereas in the period from 2016 to 2020 they lost an average of 372 gigatonnes of ice per annum7. It is likely that this melting of the ice sheets is now irreversible given that we are likely to pass 2°C8, 9.
When I think of Craig Kelly (I try not to), I think that people like him should be incarcerated for their wilful stupidity. I also wonder at the lack of intelligence of the buffoons who voted for him.