It’s that time of year for breathless reports about planetary heating. Multilateral institutions, including the United Nations, recently proclaimed 2023 the hottest year in history.
The increase in average temperature, compared to the long-term average from 1850 to 1900, was a rise of 1.48 degrees Celsius. However, with varying measurements from different sites over the years, we should approach such claims cautiously. Interested parties use them to promote ‘solutions’ that could do more harm than good. Notably, this new ‘high’ temperature was only 0.17 degrees Celsius higher than in 2016.
NASA notes five factors explaining higher temperatures, with only one being the usual suspect: greenhouse gases (mainly CO2). The other four are the El Niño Southern Oscillation (ENSO) cycle, aerosol levels (like smoke, dust, and air pollution), volcanic eruptions, and general ocean temperature trends. NASA says the first and last of these affect current overall temperature.
The world is currently in an El Niño phase, which brings much higher temperatures globally. Oceans have also been gradually warming for decades, with occasional pauses, such as from 1998 to 2013.
There are other major reasons to be skeptical of extreme claims. First, this ‘history’ is relatively short, covering only the past 150 years (or less). Second, reliable global satellite temperature measurements have only been possible since the 1970s. Before that, temperature monitoring was not systematic.
Until the 1880s, temperature recordings were mostly in North America or Europe and hence show significant data biases. Another crucial bias was that many weather stations are in or near cities, which warmed as they burned more coal (and, later on, more oil and natural gas), causing the heat island effect. Cities also grew toward the weather stations, usually located on the outskirts, especially at airports.
For example, Winnipeg has two weather stations: one at the wind-swept airport and the other downtown at the Forks. An analysis back in 2007 showed a temperature difference between the two locations to be 1.57 degrees warmer at the Forks. So closing or ignoring the airport temperature measurement location would “on paper” show warming in Winnipeg. It will be the same with most major Canadian airports.
Another way to challenge the assertion that 2023 was the hottest year is to examine other periods. The 1930s, for instance, were hotter and drier than the decades before or after, setting many records that remain unbroken. The 1970s were cool, despite rising CO2 emissions.
The Medieval Warm Period (approx. AD 750 to 1350) was much warmer than today. Farming was commonplace in Greenland, and vineyards grew in Britain. Industrialization began in the 1750s, so increased greenhouse gas emissions did not cause ancient warming. Nor did lower CO2 emissions cause the subsequent cooling of the Earth’s atmosphere, which culminated in what is now called the Little Ice Age (AD 1350 to 1850), from which we are still emerging.
Although 2023 may have set records, there is no evidence that it was the ‘hottest year’.
Its summertime. Enjoy the hot weather. Ignore the climate doomsters.
Ian Madsen is the Senior Policy Analyst at the Frontier Centre for Public Policy.
