The title of D. Gramlich’s letter, Climate change far from certain, is, in a word, nonsense. Mr. Gramlich makes wild claims without any science to support them.
In its 2014 Assessment Report, a report that took more than six years to produce and included more than 2,500 scientific expert reviewers, 800 contributing authors, and 450 lead authors from 130 countries, the International Panel on Climate Change concluded:
“Warming of the climate system is unequivocal, and since the 1950s, many of the observed changes are unprecedented over decades to millennia”
“Atmospheric concentrations of carbon dioxide, methane, and nitrous oxide have increased to levels unprecedented in at least the last 800,000 years.”
“Human influence on the climate system is clear. It is extremely likely (95-100 per cent probability) that human influence was the dominant cause of global warming between 1951-2010.”
Like many climate deniers, Gramlich cherry picks the data. The Goddard Institute of Space Studies may well report that the 10 hottest years on record include 1934 and 1953 as indicated by Gramlich but what really matters is the following quote from the very same Goddard Institute: “Earth has experienced rapid warming in the last few decades, and the most recent decade was the warmest of all.”
As for Gramlich’s whimsical notion that the Medieval Warming Period was warmer than today, the IPCC’s third assessment report, available on-line debunks that too.
The fact that grapes are not grown today in Britain like they were some 3,000 years ago as Gramlich notes, doesn’t mean the planet is colder or cooling. The key indicators of global warming are all moving in the direction expected of a warming globe. It is the long-term trends that are important; measured over decades or more, and those long-term trends show that our planet is getting hotter.