In 1981, James Hansen was the Director of the NASA Goddard Institute for Space Studies. He was also the lead author of a seminal paper published in the prestigious journal Science entitled “Climate Impact of Increasing Atmospheric Carbon Dioxide“. In the paper, Hansen and his colleagues reported (and illustrated with multiple graphs) the widely accepted 100-year (~1880-1980) record of hemispheric and global temperature changes. At the time, most climate scientists were reporting that the Northern Hemisphere’s (NH) temperatures had undergone a rapid warming of between +0.8 and +1.0°C between the 1880s and 1940. Then, after 1940 and through 1970, NH temperatures were reported to have dropped by about -0.5 to -0.6°C, a decades-long cooling trend which at the time had fomented widespread debate about global cooling in the scientific community.
Like their peers, NASA’s Hansen and his co-authors indicated that the Northern Hemisphere had warmed by ~0.8°C between the 1880s and 1940, and then cooled by ~0.5°C between 1940 and 1970.
A graph of “observed temperature” for the Northern Hemisphere was included in the paper to illustrate these climatic trends.
Today, NASA’s Goddard Institute for Space Studies is directed by Dr. Gavin Schmidt, a trained mathematician. (James Hansen retired from the position in 2013.) Schmidt’s version of the Northern Hemisphere’s temperature record for 1880-1980 looks vastly different than what his predecessor had illustrated in 1981. Instead of leaving the historically observed temperatures alone, NASA has invented new ways to portray the pre-1981 temperature history of the Northern Hemisphere.
To subjectively summarize the wholesale adjustments to past temperature data, the +0.8°C warming between 1880 and 1940 has been reduced to +0.35°C. The -0.5°C cooling between 1940 and 1970 has been reduced to -0.2°C. And in NASA’s 2017 version of Northern Hemisphere temperatures, 1980 is now even with 1940. Neither year was warmer than the other. In the original 1981 NASA graph, however, 1980 was -0.3°C colder than 1940.
If the originally recorded observations for the Northern Hemisphere had not been erased from the temperature record, the pre-1981 trend would look like it does in the graph below (black trend line). In other words, if the temperature observations as they appeared in 1981 had not been tampered with, it would be clear the Northern Hemisphere’s surface temperatures have undergone an oscillation, or warming-cooling-warming cycle, with no significant net change from the earlier warming amplitude or rate (1880-1940) to the more recent one (1980s-present).
Why Did NASA Eliminate The Early 20th Century Warming And Mid-20th Century Cooling?
The fundamental reason why NASA has manipulated past temperature data is so that the historical climate record may conform to the IPCC models that presume variations in surface temperatures are predominantly determined by anthropogenic CO2 emissions. Fossil fuels consumption in particular and anthropogenic CO2 emissions in general plodded along steadily at about 1 GtC/year (gigatons of carbon per year) during the 1900 to 1945 period. Then, after 1945, human emissions exploded. They reached 4 GtC/year by the 1970s, 6 GtC/year by the 1990s, and 10 GtC/year by 2014.
NASA recognized that (a) anthropogenic CO2 emissions were not rising much at all while the surface temperatures were rising dramatically (1880s-1940s), and that (b) surface temperatures were cooling (1940s to 1970s) while anthropogenic CO2 emissions were surging upwards. These observed trends did not support climate modeling; instead, they undermined the models. So, to counteract this, NASA has undergone a decades-long effort to change past temperature data that do not adhere to modeled expectations. In other words, NASA has sought to suppress the 1880s to 1940 warming amplitude and rate, and they have warmed up the 3 decades of NH cooling by about +0.3°C. In this way, the overall 1880s-present trend will look linear rather than oscillatory, and it will also look more and more like the trends in anthropogenic CO2 emissions (above graph). When the facts don’t fit the models, NASA apparently changes the facts.
Non-Adjusted Temperature Data Appear To Correlate With 20th Century Solar Forcing
In a paper just published in the journal New Astronomy, scientists Yndestad and Solheim (2017) have released a reconstruction of solar activity (Total Solar Irradiance, or TSI) for 1700-2013. As explained here, the 20th Century contained the so-called Modern Grand Maximum of very high solar activity.
Taking a closer look at the 20th Century solar irradiance trend only, the (a) rapid rise in TSI for 1900-1950, the (b) dramatic drop in TSI during the 1950s to 1970s, and then the (c) abrupt 1980s to early 2000s increase in TSI all seem to correspond generally to the non-adjusted temperature trend for the Northern Hemisphere — prior to the NASA temperature data manipulation.
In fact, many other recently published surface temperature reconstructions indicate that the warming-cooling-warming oscillatory 20th Century trend may correlate with this solar forcing trajectory.
Rydval et al. (2017), for example, include several graphs of surface temperatures for Northern Hemisphere locations that show warming and cooling periods largely correspond to multi-decadal- and centennial-scale records of high (warming) and low (cooling) solar activity. In the NH graphs below, for example, notice how the temperature records follow a similar track that correspond with the non-adjusted (pre-1981) NASA temperature record: (a) rapid warming from around 1900 to the mid-20th Century, (b) rapid cooling for a few decades, and then (c) another warming ascent from about the 1970s or 1980s onward. Also notice that the mid-20th Century peak warmth is not significantly different than the warmth achieved in the last decade or two, again affirming an oscillatory pattern rather than a linear one.
“[T]he recent summer-time warming in Scotland is likely not unique when compared to multi-decadal warm periods observed in the 1300s, 1500s, and 1730s … [E]xtreme cold (and warm) years observed in NCAIRN appear more related to internal forcing of the summer North Atlantic Oscillation. … There is reasonable agreement in general between the records regarding protracted cold periods which occur during the LIA and specifically around the Maunder solar minimum centred on the second half of the seventeenth century and to some extent also around the latter part of the fifteenth century coinciding with part of the Spörer minimum (Usoskin et al. 2007).”
Temperature records for many other regions within the Northern Hemisphere (as well as several from the Southern Hemisphere) may also align with the original (non-adjusted) NASA temperature observations and recent reconstructions of TSI. So as not to cross the threshold of excessiveness, only a small portion of the many similarly correlative warming-cooling-warming temperature reconstructions available are included below.
Yamanouchi, 2011 (Arctic)
Box et al., 2009 (Greenland Ice Sheet)
Hasholt et al., 2016 (Southeast Greenland)
“We determined that temperatures for the ablation measurement periods in late July to early September were similar in both 1933 and the recent period [1990s – present], indicating that the temperature forcing of ablation within the early warm period and the present are similar.”
Kobashi et al., 2011 (Greenland Ice Sheet)
Chafik et al., 2016 (Atlantic, North)
de Jong and de Steur, 2016 (Irminger Sea, North Atlantic)
Reynolds et al., 2017 (Central England, North Atlantic)
Saenger et al, 2009 (Bahamas, Northern Hemisphere)
De Jong et al., 2016 (Andes, South America)
“[T]he reconstruction…shows that recent warming (until AD 2009) is not exceptional in the context of the past century. For example, the periods around AD 1940 and from AD 1950–1955 were warmer. This is also shown in the reanalysis data for this region and was also observed by Neukom et al. (2010b) and Neukom and Gergis (2011) for Patagonia and central Chile. Similarly, based on tree ring analyses from the upper tree limit in northern Patagonia, Villalba et al. (2003) found that the period just before AD 1950 was substantially warmer than more recent decades.”
O’Donnell et al., 2016 (Southeast Australia)
de Jong et al., 2013 (Chile)
To summarize, then, there seems to be no scientific justification for NASA’s conspicuous temperature data tampering. From all appearances, the removal and/or doctoring of observed temperature data from the pre-1981 period was a tendentious act designed to change the appearance of graphs to fit climate models that presuppose a deterministic anthropogenic influence. NASA’s apparent manipulation of climate science endangers the reputation of scientists across all disciplines. It should be stopped immediately before even more credibility is lost.