What is Global Surface Temperature (GST)?

Global Surface Temperature (GST) refers to the average temperature of Earth's surface. It is calculated as a weighted average of temperatures recorded over both the ocean and land areas. This average combines sea surface temperature (SST) for oceanic regions and surface air temperature for land areas.

What are the primary sources for modern global surface temperature data?

The primary sources for contemporary global surface temperature data are weather stations located on land and measurements taken by satellites. These direct measurements provide the basis for understanding current temperature trends.

How are temperatures estimated for periods before direct instrumental records?

For estimating temperatures in the distant past, scientists utilize proxy data. These indirect sources include records derived from tree rings, corals, and ice cores, which provide valuable insights into historical climate conditions.

What is the significance of observing rising Global Surface Temperature (GST)?

Observing the rising GST over time is a key piece of evidence supporting the scientific consensus on climate change. This consensus indicates that human activities are the primary cause of the current climate change.

What are alternative terms used for Global Surface Temperature?

Alternative terms used interchangeably with Global Surface Temperature (GST) include Global Mean Surface Temperature (GMST) and Global Average Surface Temperature. These terms all refer to the same concept of Earth's average surface temperature.

When did reliable, quasi-global temperature measurements begin?

Reliable instrumental temperature records with quasi-global coverage generally began in the period between 1850 and 1880. However, the longest continuous temperature record available is the Central England temperature data series, which dates back to 1659.

What methods are used to measure temperatures in the upper atmosphere?

Temperatures in the upper atmosphere are measured using various methods, including radiosondes launched via weather balloons, a range of satellites, and aircraft. While satellites can monitor upper atmospheric temperatures, they are not typically used for measuring surface temperature changes.

How has global average temperature changed since the late 19th century?

Since the period of 1850-1900, the global average surface temperature has shown a significant warming trend. Multiple independent datasets indicate an increase of approximately 1.09°C (ranging from 0.95°C to 1.20°C) by the 2011-2020 period.

What has been the rate of warming since the 1970s?

Since 1975, global average temperature has increased at a faster rate than in any other 50-year period over at least the last 2,000 years. The increase has been roughly 0.15°C to 0.20°C per decade, reaching at least 1.1°C above 1880 levels.

What is the approximate current annual Global Mean Surface Temperature (GMST)?

The current annual Global Mean Surface Temperature (GMST) is approximately 15°C (59°F). However, monthly temperatures can fluctuate by nearly 2°C (4°F) above or below this average.

What factors can cause variability in global average temperatures despite the long-term warming trend?

Natural internal variability within the climate system, such as phenomena like the El Niño-Southern Oscillation (ENSO), can cause year-to-year fluctuations in global average temperatures, even amidst an overall warming trend.

How does the IPCC Sixth Assessment Report define Global Mean Surface Temperature (GMST)?

The IPCC Sixth Assessment Report defines GMST as the estimated global average of near-surface air temperatures over land and sea ice, and sea surface temperature (SST) over ice-free ocean regions. Changes are typically expressed as departures from a specified reference period.

What is the difference between GMST and Global Mean Surface Air Temperature (GSAT)?

While GMST includes both near-surface air temperatures and sea surface temperatures, GSAT specifically refers to the global average of near-surface air temperatures over land, oceans, and sea ice. GSAT is often used as a metric for global temperature change in climate models.

What were the main periods of observed warming in the instrumental record?

The instrumental temperature record shows significant warming occurred in two main periods: from around 1900 to 1940, and again from around 1970 onwards. A period of cooling or plateau was observed between 1940 and 1975.

What factor has been primarily attributed to the temperature plateau between 1940 and 1975?

The relative stability or slight cooling observed in global temperatures between 1940 and 1975 has been primarily attributed to the presence of sulfate aerosols. These aerosols can have a cooling effect on the planet by reflecting incoming solar radiation.

How do land temperatures compare to sea surface temperatures in terms of warming?

Land air temperatures have been warming at a faster rate than sea surface temperatures. From 1850-1900 to 2011-2020, land temperatures warmed by approximately 1.59°C, while sea surface temperatures warmed by about 0.88°C over the same period.

What has been the linear warming trend for combined land and sea temperatures from 1980 to 2020?

From 1980 to 2020, the linear warming trend for combined land and sea temperatures has been between 0.18°C and 0.20°C per decade, depending on the specific dataset used for calculation.

What is the estimated impact of urbanization on global land temperature changes?

It is considered unlikely that uncorrected effects from urbanization, land-use changes, or land cover changes have significantly biased global land temperature trends, likely by no more than 10%. However, localized urban heat island effects can be more pronounced in rapidly urbanizing areas.

What does the NASA animation of global surface temperature from 1880 to 2023 depict?

The NASA animation visualizes global surface temperature changes from 1880 to 2023. It uses colors, with blue indicating cooler temperatures and red indicating warmer temperatures, to show the progression of warming over time.

What is the instrumental temperature record?

The instrumental temperature record is a compilation of temperatures based on direct measurements of air and ocean temperatures using instruments like thermometers and electronic sensors. It does not rely on indirect reconstructions from climate proxy data.

How are global average surface temperature records typically presented?

Records of global average surface temperature are usually presented as anomalies rather than absolute values. A temperature anomaly represents the difference between the measured temperature and a reference value, typically a 30-year average.

Why are temperature anomalies used instead of absolute temperatures?

Temperature anomalies are used because they tend to be highly correlated over large distances, making them representative of temperature changes across broad areas. Anomalies are also less sensitive to changes in the observing network compared to absolute values.

What is the estimated absolute average surface temperature for the 1961-1990 period?

The Earth's average absolute surface temperature for the 1961-1990 period has been estimated at 14°C (57.2°F). This estimate, derived from spatial interpolation of observed temperatures, has an uncertainty of about 0.5°C.

What are the minimum standards for temperature measurement stations?

The U.S. National Weather Service Cooperative Observer Program has established minimum standards for instrumentation, siting, and reporting for surface temperature stations. These standards help ensure data quality and consistency.

Can existing empirical techniques identify and remove biases in temperature data?

Yes, studies have concluded that existing empirical techniques are adequate for validating the consistency of temperature data and identifying biases in station records. These corrections help preserve information about long-term trends.

What has been the trend regarding new high temperature records versus new low temperature records in recent decades?

In recent decades, new high temperature records have substantially outnumbered new low temperature records across a growing portion of the Earth's surface, indicating a clear warming trend.

Which years have been identified as the warmest in the instrumental temperature record?

The warmest years in the instrumental temperature record have predominantly occurred in the last decade (2012-2021). The World Meteorological Organization reported that 2016 and 2020 were the two warmest years since 1850, and each year from 2015 onwards has been warmer than any prior year before 2014.

What was the global average temperature anomaly for 2023 according to the Copernicus Climate Change Service?

According to the Copernicus Climate Change Service, 2023 was 1.48°C hotter than the average temperature between 1850-1900. It was declared the warmest year on record shortly after its conclusion, breaking numerous climate records.

How do natural climate variability factors like ENSO influence global temperatures?

Natural climate variability factors, such as the El Niño-Southern Oscillation (ENSO), influence global temperatures. El Niño events generally tend to increase global temperatures, while La Niña events usually lead to cooler years relative to the short-term average.

What is the typical temperature impact of strong El Niño and La Niña events?

Strong El Niño years typically result in global average temperatures rising by 0.1°C to 0.2°C, while strong La Niña events usually cause a similar drop in global average temperatures, assuming no other short-term influences like volcanic eruptions are present.

How do major volcanic eruptions affect global temperatures?

Volcanic eruptions that inject significant amounts of sulfur dioxide into the stratosphere can cause a global cooling effect for one to three years following the event. This cooling is due to the aerosols produced, which diffuse incoming solar radiation.

What is the scientific consensus regarding climate change?

There is a strong scientific consensus that the climate is changing and that human-emitted greenhouse gases are the primary driver of this change. This consensus is reflected in reports from bodies like the Intergovernmental Panel on Climate Change (IPCC).

What did the Berkeley Earth Surface Temperature group find in their 2011 assessment?

In 2011, the Berkeley Earth Surface Temperature group found that over the preceding 50 years, the land surface had warmed by 0.911°C. Their results mirrored those of earlier studies by NOAA, the Hadley Centre, and NASA's GISS, and they addressed concerns about urban heat island effects and station quality, finding they did not bias the results.

What is the 'warming stripes' visualization?

The 'warming stripes' visualization uses color-coded annual temperatures, typically transitioning from blue (cooler) to red (warmer), to depict temperature changes over time. It provides a simple yet impactful way to illustrate global warming trends, often shown for individual countries or globally.

What is the significance of the 'climate spiral' visualization?

A climate spiral, such as the one depicting monthly anomalies from 1880 to 2021, visualizes the progression of global temperature anomalies over time. It helps to illustrate the long-term warming trend and the year-to-year variations.

What is the relationship between El Niño/La Niña years and overall global warming?

El Niño years (often shown in red) tend to correlate with higher global average temperatures, while La Niña years (often shown in blue) tend to correlate with cooler global average temperatures. These phenomena represent natural variability superimposed on the longer-term global warming trend.

What are the projected global warming ranges for the late 21st century under different emission scenarios?

Projections for the late 21st century suggest global warming could reach 1.0°C to 1.8°C under very low greenhouse gas (GHG) emissions, 2.1°C to 3.5°C under an intermediate scenario, and 3.3°C to 5.7°C under a very high GHG emissions scenario. These projections are based on climate models combined with observations.

How are climate change effects expected to vary regionally?

Climate change effects are not expected to be uniform across the globe. Land areas are projected to change more rapidly than oceans, and northern high latitudes are expected to warm faster than the tropics. Melting ice, changes in the hydrological cycle, and altered ocean currents are major ways global warming will impact regional climates.

What types of proxy data are used to reconstruct past temperatures?

Proxy data used for temperature reconstruction include tree ring widths, coral growth patterns, isotope variations in ice cores, ocean and lake sediments, cave deposits, fossils, borehole temperatures, and glacier length records. These provide indirect evidence of past climate fluctuations.

What do proxy reconstructions indicate about temperatures since AD 1600?

Proxy reconstructions extending back 2,000 years suggest that global mean surface temperatures over the last 25 years have been higher than any comparable period since AD 1600, and likely since AD 900. These reconstructions also indicate a Little Ice Age centered around AD 1700 and a Medieval Warm Period around AD 1000, though the latter was not a global phenomenon.

What historical records, besides natural proxies, can inform us about past climate variations?

Besides natural proxies, historical records such as accounts of frost fairs on the Thames, records of harvests, dates of spring events like blossom or lambing, and reports of unusual floods or droughts can be used to infer historical temperature variations, though often in a more qualitative manner.

What is the significance of ice cores in understanding Earth's climate history?

Ice cores, particularly those from Antarctica like the EPICA core reaching back 800,000 years, provide invaluable data on past climate. They record not only temperature changes but also information about global biogeochemical cycles, climate dynamics, and abrupt climate shifts across multiple glacial-interglacial cycles.

What do Greenland ice cores reveal about climate change?

Greenland ice cores provide clear records of abrupt climate changes with high time resolution. Analysis of trapped gases, like methane, in these cores also offers insights into variations in global wetland areas and greenhouse gas concentrations, contributing to our understanding of global temperature records.

What does geologic evidence, such as sediment cores, tell us about long-term climate patterns?

Sediment cores reveal that Earth's climate history includes cycles of glacials and interglacials, which are part of a long-term deepening phase of an ice age that began around 40 million years ago with the glaciation of Antarctica. These gradual changes are sometimes attributed to continental drift.

What is the primary reason cited for the claim that global warming 'stopped in 1998'?

The claim that global warming 'stopped in 1998' often arises from a misunderstanding or misrepresentation of internal climate variability. This variability, driven by complex interactions within the climate system like ENSO, can cause temporary fluctuations or slowdowns in warming rates, but does not negate the long-term warming trend.

How does internal climate variability, like La Niña, affect observed temperature trends?

Internal climate variability, such as a strong La Niña event, can temporarily push global temperatures downward. For instance, the period from 2007 to 2012 saw a slowdown in warming rates, likely influenced by such natural modes of variability.

What is the role of the World Meteorological Organization (WMO) in global temperature monitoring?

The World Meteorological Organization (WMO) plays a role in standardizing methods for land and sea temperature measurements through its Global Observing System. It also issues reports on the state of the global climate, including data on temperature trends and warmest years.

What is the significance of the 'warming stripes' graphic created by Ed Hawkins?

Ed Hawkins' 'warming stripes' graphic is a simple visualization that uses color-coded annual temperatures to show global warming trends from 1850 onwards. It has been widely adopted to communicate the reality and progression of climate change to the public.

Global Surface Temperature Wiki: Global Temperature Dynamics: An Earth Science Overview

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Understanding Global Surface Temperature

Definition

Global Surface Temperature (GST) represents the average temperature of Earth's surface, encompassing both land and ocean temperatures. It is calculated as a weighted average of surface air temperature over land and sea surface temperature over oceans. Observing the rising GST is a key indicator supporting the scientific consensus on anthropogenic climate change.

Historical Context

Reliable instrumental temperature records began emerging between 1850 and 1880. The longest continuous record, the Central England temperature series, dates back to 1659. While satellites monitor upper atmosphere temperatures, surface measurements rely on weather stations and ships. For periods prior to instrumental records, scientists utilize proxy data from sources like tree rings, corals, and ice cores to reconstruct past temperatures.

The Warming Trend

Since the mid-20th century, particularly from 1975 onwards, global surface temperatures have shown a marked increase, averaging approximately 0.15°C to 0.20°C per decade. This trend signifies a warming of about 1.1°C above pre-industrial (1850-1900) levels. The rate of warming observed in recent decades is unprecedented over at least the last two millennia.

Instrumental Temperature Records (1850-Present)

Total Warming and Trends

From 1850-1900 to 2011-2020, global average surface temperature has increased by approximately 1.09°C. This warming trend has accelerated significantly since the 1970s. Land areas are warming faster than oceans, with the Arctic experiencing particularly rapid warming. While natural variability (like ENSO) causes short-term fluctuations, the long-term upward trend is undeniable.

Warmest Years and Decades

The warmest years recorded have predominantly occurred in the 21st century. Since 2015, each year has surpassed previous records. The 2011-2020 decade was the warmest on record, continuing a pattern where each successive decade is warmer than the last. For instance, 2023 was recorded as 1.48°C warmer than the 1850-1900 average.

The following table, based on NOAA data, highlights the top 10 warmest years on record:

**Top 10 Warmest Years (NOAA Data, 1880-Present)**
Rank	Year	Anomaly °C	Anomaly °F
1	2024	1.29	2.23
2	2023	1.17	2.11
3	2016	1.00	1.80
4	2020	0.98	1.76
5	2019	0.95	1.71
6	2015	0.93	1.67
7	2017	0.91	1.64
8	2022	0.86	1.55
9	2021	0.84	1.51
10	2018	0.82	1.48

Measurement Methodologies

Data Sources

Global surface temperature data is compiled from various sources: land-based weather stations (often housed in Stevenson screens for protection), ships, and moored/drifting buoys measuring ocean temperatures. Satellite measurements provide data for the upper atmosphere but are less commonly used for direct surface temperature analysis. Data is collected globally, though coverage is sparser in polar regions and certain continents.

Anomalies vs. Absolute Values

Temperature records are typically presented as anomalies—the difference between a measured temperature and a long-term average (baseline period, usually 30 years). Anomalies are used because they correlate well over large distances and are less sensitive to variations in station location or instrumentation compared to absolute temperatures. The absolute global average temperature is estimated around 14°C (57.2°F) for the 1961-1990 period, but adding anomalies to this figure does not yield precise yearly absolute temperatures due to uncertainties.

Key Datasets

Several independent scientific organizations maintain global temperature datasets, including:

NASA's Goddard Institute for Space Studies (GISS)
NOAA's National Centers for Environmental Information (NCEI)
The UK Met Office Hadley Centre (HadCRUT)
Berkeley Earth

These datasets generally show strong agreement regarding long-term trends and variability.

Factors Influencing Global Temperature

Greenhouse Gases

The primary driver of current global warming is the increase in atmospheric greenhouse gases, such as carbon dioxide (CO2) and methane. These gases trap outgoing thermal radiation, warming the planet through the greenhouse effect. Human activities, particularly the burning of fossil fuels and land-use changes, are the main source of these increased concentrations.

Ocean-Atmosphere Interactions (ENSO)

Natural climate variability plays a significant role in short-term temperature fluctuations. The El Niño-Southern Oscillation (ENSO) is a key example. El Niño phases tend to correlate with warmer global average temperatures, while La Niña phases tend to correlate with cooler periods, relative to the long-term trend.

Aerosols and Volcanic Activity

Atmospheric aerosols, both from natural sources (like volcanic eruptions) and human activities, can influence global temperatures. Large volcanic eruptions injecting sulfur dioxide into the stratosphere can cause temporary global cooling (lasting 1-3 years) by reflecting solar radiation. Conversely, certain aerosols can contribute to warming.

Land Use and Solar Cycles

Changes in land use, such as deforestation, can affect temperature through altered greenhouse gas emissions and changes in surface albedo (reflectivity). Variations in incoming solar radiation, primarily driven by the ~11-year solar magnetic activity cycle, have a minor influence compared to greenhouse gas forcing.

Reconstructing Past Climates

Proxy Data: Tree Rings and Corals

Before the instrumental era, scientists use proxy data to estimate past temperatures. Tree rings, coral growth bands, and isotopic analysis of ice cores provide annual or near-annual records. These proxies reveal patterns like the Medieval Warm Period (around AD 1000, though not globally uniform) and the Little Ice Age (centered around AD 1700).

Ice Core Records

Ice cores drilled in Greenland and Antarctica offer invaluable long-term climate archives, extending back hundreds of thousands of years. Trapped air bubbles reveal past atmospheric composition (like CO2 and methane concentrations), while isotope ratios indicate temperature variations. These records show cycles of glacial and interglacial periods, confirming the significant influence of greenhouse gases over geological timescales.

Antarctic ice cores, such as those from Dome C, provide records spanning 800,000 years, capturing multiple glacial-interglacial cycles. Greenland ice cores offer high-resolution data on abrupt climate shifts. Comparing Greenland and Antarctic ice cores reveals variations in the latitudinal distribution of methane sources, providing insights into global biogeochemical cycles and climate dynamics.

Geologic Evidence (Millions of Years)

On geological timescales (millions of years), sediment cores and other geological evidence reveal long-term climate shifts. Earth's climate has undergone significant changes due to factors like continental drift. The current ice age began approximately 40 million years ago with Antarctica's glaciation, intensifying about 3 million years ago with the formation of Northern Hemisphere ice sheets.

Robustness of Evidence

Scientific Consensus

There is a strong scientific consensus, supported by major scientific bodies like the Intergovernmental Panel on Climate Change (IPCC) and the U.S. Global Change Research Program, that Earth's climate is changing and that human-emitted greenhouse gases are the primary driver. Multiple independent datasets and methodologies corroborate the observed warming trends.

Addressing Skeptical Concerns

Studies have rigorously examined potential biases in temperature data, such as the urban heat island effect and station quality. Research indicates that even when accounting for these factors, the overall warming trend remains consistent across different datasets and methodologies, confirming the robustness of the findings.

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References

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Global Temperature Dynamics

💡 Dive in with Flashcard Learning! 💡

Understanding Global Surface Temperature 🌍

🌡️ Definition

📊 Historical Context

📈 The Warming Trend

Instrumental Temperature Records (1850-Present) 📅

⬆️ Total Warming and Trends

☀️ Warmest Years and Decades

Measurement Methodologies 🔬

🛰️ Data Sources

🧮 Anomalies vs. Absolute Values

📊 Key Datasets

Factors Influencing Global Temperature ☀️

💨 Greenhouse Gases

🌊 Ocean-Atmosphere Interactions (ENSO)

🌋 Aerosols and Volcanic Activity

🌳 Land Use and Solar Cycles

Reconstructing Past Climates ⏳

🌳 Proxy Data: Tree Rings and Corals

🧊 Ice Core Records

🌍 Geologic Evidence (Millions of Years)

Robustness of Evidence ✅

🧑‍🔬 Scientific Consensus

🧐 Addressing Skeptical Concerns

Teacher's Corner 🧑‍🏫

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📜 Important Notice

Dive in with Flashcard Learning!

Understanding Global Surface Temperature

Definition

Historical Context

The Warming Trend

Instrumental Temperature Records (1850-Present)

Total Warming and Trends

Warmest Years and Decades

Measurement Methodologies

Data Sources

Anomalies vs. Absolute Values

Key Datasets

Factors Influencing Global Temperature

Greenhouse Gases

Ocean-Atmosphere Interactions (ENSO)

Aerosols and Volcanic Activity

Land Use and Solar Cycles

Reconstructing Past Climates

Proxy Data: Tree Rings and Corals

Ice Core Records

Geologic Evidence (Millions of Years)

Robustness of Evidence

Scientific Consensus

Addressing Skeptical Concerns

Teacher's Corner

True or False?

Test Your Knowledge!

Gamer's Corner

Discover other topics to study!

References

Feedback & Support

Disclaimer

Important Notice