They avoid some of the issues in Millar by using more globally - representative surface temperature records, though they still use series that blend surface air temperatures over land with slower - warming sea
surface temperatures over the ocean.
While consistent with the IPCC assessments of historical warming, it lacks coverage of much of the fast - warming Arctic region and blends surface air temperatures over land with slower - warming sea
surface temperatures over the ocean.
Increasing
the surface temperature over the ocean by 1 °C should increase the humidity of saturation and thus the absolute humidity by 8 percent.
Not exact matches
While this is bad news for the planet, it's good news for climate change scientists who have — for the last two decades — puzzled
over warming trends in
ocean surface temperatures for nearly 20 years.
They include higher sea
surface temperatures over the Indian
Ocean, which can lead to greater rainfall
over the sea rather than on land.
The other global flu pandemics
over the past century — in 1957, 1968 and 2009 — also followed cooler sea
surface temperatures in the Pacific
Ocean.
Analyzing data collected
over a 20 - month period, scientists from NASA's Goddard Space Flight center in Greenbelt, Md., and the Massachusetts Institute of Technology found that the number of cirrus clouds above the Pacific
Ocean declines with warmer sea
surface temperatures.
Land and
Ocean Combined: The combined average temperature over global land and ocean surfaces for August 2014 was the record highest for the month, at 61.45 °F (16.35 °C), or 1.35 °F (0.75 °C) above the 20th century average of 60.1 °F (15.6
Ocean Combined: The combined average
temperature over global land and
ocean surfaces for August 2014 was the record highest for the month, at 61.45 °F (16.35 °C), or 1.35 °F (0.75 °C) above the 20th century average of 60.1 °F (15.6
ocean surfaces for August 2014 was the record highest for the month, at 61.45 °F (16.35 °C), or 1.35 °F (0.75 °C) above the 20th century average of 60.1 °F (15.6 °C).
The global average
temperature over land and
ocean surfaces for January to October 2014 was the highest on record, according to the U.S. National Oceanic and Atmospheric Administration (NOAA).
Instead, the researcher and his colleagues use historic measurements of air pressure and
ocean temperatures, put into a model, to calibrate
surface temperatures over the 20th century.
According to NOAA scientists, the globally averaged
temperature over land and
ocean surfaces for August 2014 was the highest for August since record keeping began in 1880.
The high October
temperature was driven by warmth across the globe
over both the land and
ocean surfaces and was fairly evenly distributed between the Northern and Southern Hemispheres.
El Niño thus leaves its mark on the Quelccaya ice cap as a chemical signature (especially in oxygen isotopes) indicating sea
surface temperatures in the equatorial Pacific
Ocean over much of the past 1,800 years.
Scientists working off the California coast use chemical - sniffing probes, robotically driven subs, and seafloor - tethered
temperature sensors to watch flows of lava pave
over a once - thriving ecosystem at hydrothermal vents several kilometers below the
ocean's
surface.
El Niño is a weather pattern characterized by a periodic fluctuation in sea
surface temperature and air pressure in the Pacific
Ocean, which causes climate variability
over the course of years, sometimes even decades.
The effects of wind changes, which were found to potentially increase
temperatures in the Southern
Ocean between 660 feet and 2,300 feet below the surface by 2 °C, or nearly 3.6 °F, are over and above the ocean warming that's being caused by the heat - trapping effects of greenhouse g
Ocean between 660 feet and 2,300 feet below the
surface by 2 °C, or nearly 3.6 °F, are
over and above the
ocean warming that's being caused by the heat - trapping effects of greenhouse g
ocean warming that's being caused by the heat - trapping effects of greenhouse gases.
Winds
over the Atlantic
Ocean also appear to modulate global
surface temperatures, albeit to a lesser extent than those
over the Pacific
Ocean.
Changes in the
temperature of the sea
surface in the Indian and Atlantic
Oceans are linked to the pattern of rainfall
over parts of the surrounding continents.
Note that we've got a paper soon to come out in «The Cryosphere» (and we'll have a poster at AGU) looking at recent «Arctic Amplification» that you discuss (the stronger rise in
surface air
temperatures over the Arctic
Ocean compared to lower latitudes).
Additionally, the paper supports the theory that heat storage in the deep
ocean may be partly responsible for the parallel pause in Earth's
surface temperatures over the past 13 years.
However, for the globe as a whole,
surface air
temperatures over land have risen at about double the
ocean rate after 1979 (more than 0.27 °C per decade vs. 0.13 °C per decade), with the greatest warming during winter (December to February) and spring (March to May) in the Northern Hemisphere.
The most important bias globally was the modification in measured sea
surface temperatures associated with the change from ships throwing a bucket
over the side, bringing some
ocean water on deck, and putting a thermometer in it, to reading the thermometer in the engine coolant water intake.
Surface specific humidity has generally increased after 1976 in close association with higher
temperatures over both land and
ocean.
The observed fact that
temperatures increases slower
over the
oceans than
over land demonstrates that the large heat capacity of the
ocean tries to hold back the warming of the air
over the
ocean and produces a delay at the
surface but nevertheless the atmosphere responds quit rapidly to increasing greenhouse gases.
Warming has occurred in both land and
ocean domains, and in both sea
surface temperature (SST) and nighttime marine air
temperature over the
oceans.
Global mean
temperatures averaged
over land and
ocean surfaces, from three different estimates, each of which has been independently adjusted for various homogeneity issues, are consistent within uncertainty estimates
over the period 1901 to 2005 and show similar rates of increase in recent decades.
Each layer of water can have drastically different
temperatures, so determining the average
over the entirety of the
ocean's
surface and depths presents a challenge.
The former is likely to overestimate the true global
surface air
temperature trend (since the
oceans do not warm as fast as the land), while the latter may underestimate the true trend, since the air
temperature over the
ocean is predicted to rise at a slightly higher rate than the
ocean temperature.
The globally averaged
temperature over land and
ocean surfaces for February 2017 was the second highest for the month.
The globally averaged
temperature over land and
ocean surfaces for March 2017 was the second highest for the month.
In March, 2018, lower tropospheric
temperatures (1500m)
over the
oceans (71 % of the earth's
surface) also saw a further drop:
Ocean surfaces have warmed considerably
over the last few years, and since
oceans cover roughly tw0 - thirds of the globe's area, it is reasonable to examine how sea
surface temperature evolution has played into the short - term evolution of GMST.
A well - known issue with LGM proxies is that the most abundant type of proxy data, using the species composition of tiny marine organisms called foraminifera, probably underestimates sea
surface cooling
over vast stretches of the tropical
oceans; other methods like alkenone and Mg / Ca ratios give colder
temperatures (but aren't all coherent either).
The globally averaged
temperature over land and
ocean surfaces for 2015 was the highest among all years since record keeping began in 1880.
There are some various proposed mechanisms to explain this that involve the
surface energy balance (e.g., less coupling between the ground
temperature and lower air
temperature over land because of less potential for evaporation), and also lapse rate differences
over ocean and land (see Joshi et al 2008, Climate Dynamics), as well as vegetation or cloud changes.
Cooling sea -
surface temperatures over the tropical Pacific
Ocean — part of a natural warm and cold cycle — may explain why global average
temperatures have stabilized in recent years, even as greenhouse gas emissions have been warming the planet.
In addition, since the global
surface temperature records are a measure that responds to albedo changes (volcanic aerosols, cloud cover, land use, snow and ice cover) solar output, and differences in partition of various forcings into the
oceans / atmosphere / land / cryosphere, teasing out just the effect of CO2 + water vapor
over the short term is difficult to impossible.
More than 95 % of the 5 yr running mean of the
surface temperature change since 1850 can be replicated by an integration of the sunspot data (as a proxy for
ocean heat content), departing from the average value
over the period of the sunspot record (~ 40SSN), plus the superimposition of a ~ 60 yr sinusoid representing the observed oceanic oscillations.
This plot shows thermosteric sea level change
over that period, which would strongly correlate with OHC /
ocean temperature, and this plot shows
surface temperature evolution.
Soundbite version: «Global warming is expected to increase sea
surface temperatures, create a thicker and warmer
ocean surface layer, and increase the moisture in the atmosphere
over the
oceans — all conditions that should lead to a general increase in hurricane intensity and maybe frequency.»
The two longest ones are of
temperature near the Earth's
surface: a vast network of weather stations
over land areas, and ship data from the
oceans.
I acknowledge that
temperature variations can vary
over the earth's
surface, and that heat can be stored / released by vertical processes in the atmosphere and
ocean.
El Niño: A phenomenon in the equatorial Pacific
Ocean characterized by a positive sea
surface temperature departure from normal (for the 1971 - 2000 base period) in the Niño 3.4 region greater than or equal in magnitude to 0.5 degrees C (0.9 degrees Fahrenheit), averaged
over three consecutive months.
If global
surface temperatures continue not to increase v quickly
over the next decade or two then I think this could seriously slow down action to cut GHG emissions, no matter how well understood the «slow - down» is, and no matter how much additional heat is measured accumulatng in the
oceans.
According to the investigation: «There is a strong increasing trend in sea
surface temperature over the northern Indian
Ocean during the 1952 - 96 time period» and «Soot was a sizeable fraction of the aerosol mix and caused substantial absorption of solar radiation.
«The combined average
temperature over global land and
ocean surfaces tied with 2010 as the highest on record for April, at 58.09 °F (14.47 °C) or 1.39 °F (0.77 °C) above the 20th century average.»
The key points of the paper are that: i) model simulations with 20th century forcings are able to match the
surface air
temperature record, ii) they also match the measured changes of
ocean heat content
over the last decade, iii) the implied planetary imbalance (the amount of excess energy the Earth is currently absorbing) which is roughly equal to the
ocean heat uptake, is significant and growing, and iv) this implies both that there is significant heating «in the pipeline», and that there is an important lag in the climate's full response to changes in the forcing.
Now since relative humidity remains roughly constant at the
ocean surface and the air's capacity to hold water increases with
temperature, relative humidity will actually decrease
over land, particularly as one enters the continental interiors.
Given all the independent lines of evidence pointing to average
surface warming
over the last few decades (satellite measurements,
ocean temperatures, sea - level rise, retreating glaciers, phenological changes, shifts in the ranges of
temperature - sensitive species), it is highly implausible that it would lead to more than very minor refinements to the current overall picture.
Maue discussed how «two camps» of researchers claim to have increased predictability of such weather events
over periods of a month or more by using clues either in the Arctic, related to the extent of sea ice and snow cover, or in the
temperature of
surface waters across the Pacific
Ocean.