L’any passat va ser el segon més rècord del rècord del món, però en molts llocs, com Austràlia i Alaska, les temperatures van ser sense precedents en el manteniment de registres moderns. Això es coneix a partir de les dades recollides per termòmetres a la superfície de la Terra i analitzades per agències com la NASA, NOAA i la UK Met Office.
Però l’orbitació a l’espai és una altra font de lectures globals de temperatura que poden funcionar com un dels molts controls en els instruments de superfície. Els satèl·lits Aqua i Terra de la NASA poden detectar energia tèrmica a la superfície terrestre i s’utilitzen per intuir les temperatures superficials de la terra.
Australia, colored a crimson red, sticks out on the global map.
Last year was the second-warmest on record for the globe, but in many places, such as Australia and Alaska, temperatures were unprecedented in modern record-keeping. This is known from data gathered by thermometers at the Earth’s surface, and analyzed by agencies such as NASA, NOAA and the U.K. Met Office.
But orbiting in space is another source of global temperature readings that can operate as one of many checks on the surface instruments. NASA’s Aqua and Terra satellites can detect thermal energy at the Earth’s surface and are used to sense land surface temperatures.
Though the data set is far more limited than the surface records, the satellite data can help reveal interesting patterns to how climate change is playing out around the world.
Descartes Labs, a Santa Fe-based company that operates a huge repository of geospatial data for use in building predictive models for anything from environmental indicators to financial data, examined data from the Aqua and Terra satellites going back to 2003 and provided it to The Washington Post.
Descartes Labs and The Post’s graphics team produced these maps that show temperature rankings over different periods of time.
According to Descartes Labs, the consistency of the remotely sensed data as well as its high resolution of one kilometer makes it useful for comparing long time spans.
The top map shows areas that had one of their top five warmest years in 2019. Immediately the warmth in Australia, Alaska, Europe, most of Africa, South America, Greenland and Southeast Asia pop out. The main exceptions are large parts of the United States and Canada, which did not experience record warmth in 2019.
The map below highlights only those areas that had their warmest year on record in 2019.
Where 2019 was the hottest recorded year
NASA satellite imagery (since 2003)
Berkeley Earth land-based temperature observations (since 2003)
One can compare the space-based temperature measurements with surface data (shown in the above map below the satellite data), and they pretty much tell the same story. Australia was extraordinarily hot, and also experienced record dryness, before its devastating bush fire season that still continues. Alaska, parts of Europe, Africa, Southeast Asia and Mexico also saw record warmth, according to both data sources.
Where 2019 was the hottest year since 2003
New South Wales
The extraordinary heat in Australia is worth zooming in on in its own right (above). The country was never as hot and as dry at the same time as it was in 2019. In December, Australia recorded its two hottest days on record. On Dec. 18, the nationally-averaged maximum temperature was 107.4 degrees Fahrenheit (41.9 Celsius), shattering the old record of 104.5 degrees (40.3 Celsius) set in 2013.
The heat and drought conditions led to unprecedented bush fires that consumed huge tracts of forests rich in biodiversity, particularly in Victoria and New South Wales. The fires in 2019 and 2020 have killed more than two dozen people, effectively doubled the country’s greenhouse gas emissions and led to a political crisis for pro-coal development Prime Minister Scott Morrison. The fires have killed as many as 1 billion animals, and likely pushed many species beyond the brink of extinction.
Coinciding with a large patch of scarlet on the map, some of the most destructive bush fires struck between Sydney and southeastern Queensland. Climate change has led to more frequent and intense heat waves in Australia, and has increased a key metric used to predict fire severity to unprecedented levels, known as the Forest Fire Danger Index.
Australia has warmed by just over 1.8 degrees (1 degree Celsius) since 1910, with most of the warming occurring since 1950. Australia’s Bureau of Meteorology has found an uptick in the frequency of extreme heat events and severity of drought conditions during this period, as well.
In all surface temperature data sets, 2016 was the warmest year on record, coinciding with a record strong El Niño event in the tropical Pacific Ocean. Such events tend to boost global average temperatures by adding a large amount of heat to the near surface waters of the tropical Pacific, as well as adding heat to the atmosphere.
The red areas in the composite maps above are regions where that particular year was the hottest within the 2003 to 2018 time period.
The Washington Post’s climate team has also produced its own analysis, based upon surface temperature observations, showing the parts of the world where warming has already exceeded the agreed upon temperature target of 2 degrees Celsius, or 3.6 degrees Fahrenheit.