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A viral X post mentions that the year 1979 was intentionally selected as the starting point for temperature and sea ice graphs to mislead people by exaggerating warming trends.
The post with more than 29200 views has a caption, “1979 was the coldest year on record in Iceland. That is why #ClimateScam professionals chose to start their temperature and sea ice graphs in 1979.” The post has following claims:
Claim 1: 1979 was the coldest year in Iceland, and climate scientists selected it as the starting point for temperature and sea ice graphs to manipulate data.
This claim argues that climate scientists deliberately chose 1979 as the starting point for data to exaggerate warming trends. The premise suggests manipulation rather than a scientific basis for this choice.
Fact 1: 1979 is used because it marks the beginning of satellite-era data collection.
The selection of 1979 as a reference year for many climate datasets, including sea ice and temperature graphs, is not arbitrary. Instead, it corresponds to the advent of satellite-based Earth observation systems. These satellites provide high-resolution, consistent, and global data, making them the most reliable source for monitoring climate variables such as sea ice extent, surface temperatures, and atmospheric patterns.
Before 1979, sea ice measurements relied on sporadic and localized data from ship logs, aircraft surveys, and coastal observations, which lacked the global coverage and accuracy that satellites offer. Using 1979 as a baseline ensures the data is consistent and comparable over time.
Since 1979, satellites have provided a continuous and nearly comprehensive record of Earth’s sea ice cover. These satellites use sensors that detect microwaves emitted by the ice surface, enabling data collection year-round, even during the long polar night when visible light is unavailable. Unlike visible light, microwave energy can penetrate clouds, ensuring consistent observations regardless of weather conditions.
The continuous sea ice record began with the Scanning Multichannel Microwave Radiometer (SMMR) aboard the Nimbus-7 satellite (1978–1987). This was followed by the Special Sensor Microwave/Imager (SSM/I) and the Special Sensor Microwave Imager Sounder (SSMIS) on the Defense Meteorological Satellite Program (DMSP) satellites (1987 to present). Additional contributions came from the Advanced Microwave Scanning Radiometer for EOS (AMSR-E) on NASA’s Aqua satellite (2002–2011) and its successor, the Advanced Microwave Scanning Radiometer 2 (AMSR2), launched in 2012 on JAXA’s GCOM-W1 satellite.
Between 1979 and 2015, the extent of Arctic sea ice in September showed a significant decline, averaging a 13.4% reduction per decade. Across all geographic regions, months, and seasons, the Arctic sea ice extent today is lower than it was in the 1980s and 1990s.
This decline is influenced by both natural variability and global warming. For example, the Arctic Oscillation (AO), which was strongly positive through the mid-1990s, contributed to the loss of thicker, older ice by pushing it out of the Arctic. This older, multiyear ice was replaced by thinner first-year ice, which is more susceptible to melting. After the mid-1990s, the AO shifted to neutral or negative phases, yet Arctic sea ice did not recover. Instead, an accelerated decline began around 2002. This pattern was likely initiated by the AO but sustained and exacerbated by unusually warm Arctic air temperatures, driving continued melting into the following decade.
Reliable records of Arctic sea ice date back to 1953, with near-continuous monitoring provided by satellites since 1979. Source: NASA
Was 1979 the coldest year in Iceland?
While 1979 was indeed a colder-than-average year in some regions, such as Iceland, this local anomaly does not undermine the broader scientific rationale for using 1979 as a baseline year. Climate data analysis is global in scope, and individual regional anomalies do not invalidate global trends.
The Broader Context of Warming Trends
Even if 1979 were removed as the starting point, the long-term warming trend remains evident. Data from earlier decades, such as the 1950s and 1960s, also show significant warming when compared to pre-industrial levels. Manipulation of starting points would not mask the undeniable upward trajectory of global temperatures due to greenhouse gas emissions.
Claim 2: Cooling Trends Disprove Global Warming.
This claim suggests that observed short-term cooling trends or fluctuations are evidence against the broader concept of global warming.
Fact 2: Short-term cooling trends are consistent with long-term climate change.
Climate change refers to long-term trends and patterns, not short-term variations. The climate system is influenced by numerous factors, including volcanic activity, solar radiation, oceanic cycles like El Niño and La Niña, and human activities. Short-term cooling trends often arise due to these natural factors and do not negate the overarching warming trend.
Examples of Short-Term Variability
- The 1998-2012 “Hiatus”: During this period, global surface temperatures rose more slowly, leading to claims of a “pause” in global warming. Subsequent research revealed that ocean heat uptake, particularly in the Pacific, temporarily dampened surface warming. When accounting for ocean heat content, the warming trend was uninterrupted.
- Volcanic Eruptions: Major eruptions, such as Mount Pinatubo in 1991, release aerosols into the atmosphere that reflect sunlight and cause temporary cooling. These events are well-documented and accounted for in climate models.
- La Niña Events: La Niña, the cooler counterpart to El Niño, can temporarily lower global temperatures by enhancing the cooling of ocean surface waters. These natural cycles are part of normal climate variability.
The Big Picture
Long-term data overwhelmingly show a consistent warming trend. For example, the Intergovernmental Panel on Climate Change (IPCC) has repeatedly documented the increase in global mean temperatures, sea level rise, shrinking glaciers, and declining Arctic sea ice. These changes align with predictions based on increasing atmospheric greenhouse gas concentrations. Analysis of global temperature records from multiple independent sources, such as NASA, NOAA, and the UK Met Office, confirms that the Earth has warmed by approximately 1.1°C (2°F) since the late 19th century. This warming is unprecedented in the context of natural variability observed over millennia.
References:
https://earthobservatory.nasa.gov/features/SeaIce
https://svs.gsfc.nasa.gov/5170
https://www.ipcc.ch/2021/08/09/ar6-wg1-20210809-pr
https://svs.gsfc.nasa.gov/3802
Banner Image: Photo by Raul Koženevski https://www.pexels.com/photo/snow-covered-peaks-by-the-arctic-ocean-29474366/
