Heat
Clouds reflect 59-60 W per square meter and the atmosphere 1/3 that much.
Reflection off ice and snow is more typically in the low 70%’s. Absorption by water without ice and snow depends greatly on the sun angle: 94% when the sun is overhead, but much less at the angle becomes more glancing.
This page contains 14 graphs of Earth's temperature history over the past 600 million years, over ever shorter time spans. The 600-million-year graph below uses surface temperatures, but the graph below it uses deep ocean ones. Until the past century, the fastest warming shown below has been about 0.4°C per century.
The following pages contain articles about heat, arranged in 10 major groups: US Temperatures, Ocean Heat, Warming Outside the US, World Temperatures, Heating Patterns, Paleo-Temperature Records (see the graphs just below), Future Temperatures, Clouds & Heat, Sulfates & Cooling, and Temperature Sensitivity (& Speed) to Doubled CO2. The many articles on permafrost and seabed methane hydrates are found on the Carbon + & - page.
Month and year follow each article's name. PDF files are so marked, after month and date, some with authors noted. Within sections, more recent files appear above older files.
What's the Hottest Earth Has Ever Been? 0620 for above figure - 3,700°F in Hadean era, not long after formation of Earth, in the aftermath of the Moon's formation. Since Snowball Earth about 800 million years ago (Mya), Earth's average surface temperatures reached around 90°F repeatedly, as recently as 92 Mya. 73-82°F during PETM, 55 Mya. Earth's surface is currently near 60°, during an interglacial, but with much ice still at both poles. Since Snowball Earth, our planet has rarely been as cold as the ice ages of the past 2-3 million years, since long ice ages ending about 270 Mya (and starting as plants began colonizing land 370 Mya).
Above are preliminary results from Smithsonian.
Below is a less detailed and older graph. Temperatures (and CO2 levels) are approximate.
A
67 million years of temperature data from NOAA.
Below is a 2nd view.
Below that is a 3rd view.
The PETM warming spike 55 million years ago was ~ 4 to 5°C (or 6°C, estimate not shown here) over just 10,000 years. That’s 0.04 to 0.06°C / century.
Temperature variation from peak to nadir increased, espcially over the last 1-2 million years, after North America joined South America.
Temperature rose from -7°C to +2 to 4°C over “short” time spans 18,000, 130,000, 240,000, and 330,000 years ago.
Temperatures at left are from the ice surface at the time, rather than from the deep ocean (above). Earth’s surface may have warmed 50% as fast as the south pole / Vostok, better 62% (Snyder 2016).
Vostok warmed ~8°C from 18,000 to 10,000 years ago, which is ~0.1°C / century. However, polar regions have warmed almost twice as fast the planet as a whole. So, warming was 0.03 to 0.05°C / century worldwide.
Polar warming ~ 130,000 years ago was almost 10°C over only ~8,500 years, ~20% faster. Globally that’s 0.035 to 0.055°C / century.
The temperature / CO2 concentrations from the Vostok ice core (graph above this one) are shown as blue dots on the left hand side. The two trend lines show the best fits to that data in CO2 space, one for CO2 alone (purple) and one for CO2 plus CH4 (methane) in green.
After adjustment to global temperatures (right vertical axis) from Antarctic (Vostok) temepratures (left vertical axis), the trend lines from eras colder than today are remarkably consistent with temperatures from eras hotter than today. This gives us some confidence that the more distant past and the more recent past are reasonable guides to our temperature future, about 5°C hotter than 1951-80, given CURRENT CO2 levels.
Current CH4 levels are about 170% above pre-industrial levels, while CO2 levels are about 50% above pre-industrial levels. So 9°C hotter than 1951-80 may be in our future, unless we reduce CO2 and CH4 levels.
Earth warmed (scale at left) by 0.6°C (0.4°C less -0.2°C) from 11,400 to 9,600 years ago. This rate was 0.033°C / century.
That’s slightly slower than the rate ~130,000 years ago, and somewhat slower than the rate from 18,000 to 11,400 years ago.
Below is the "Previous data”, which was based on land indicators only. The above adds ocean indicators.
This also suggests that our current interglacial period warming peaked about 7000 years ago. So we have been heading slowly into the next ice age. Milankovich cycle at work. A Medieval warm period peaked ~900 AD. Three Little Ice Ages show up around 1250 AD, 1500 AD, and 1750 AD. The descent into the next glacial period was interrupted about 1750 AD, with cool (volcano) blips 1815-1820 and 1885-1890.
However, temperatures changes in northern hemisphere SUMMERS. Due to cyclical changes in Earth’s orbit, temperatures actually ROSE during nothern hemisphere WINTERS since 7,000 years ago, as CO2 concentration gradually rose, from about 260 ppm to 280 ppm. (Baker 2017, re Marcotte)
Another perspective on the same time period, based on multiple studies and methods.
Gray is from boreholes.
This graph, especially the magenta line, suggests Little Ice Ages from 1100 to 1300 AD, again about 1550 to 1720 AD, and again from 1780 to 1870 AD. The Viking Greenland colony died out during the 1st. The current warming appears much larger than in the Medieval Warm Period, which peaked about 1,000 AD.
Research in 2012 indicated the 2nd was due to Columbus and other Europeans introducing their diseases to North America, which wiped out most of the people there, so the forests grew back, removing lots of CO2 from the air.
Some have connected the latter part of the 2nd Little Ice Age to the lack of sunspots during the Maunder Minimum from 1645 to 1715 AD. (Observations during the satellite era show that solar output is slightly (0.04%) lower in periods with few sunspots and slightly higher (0.04%) when sunspots peak. Sunspots during the most recent solar minima in 2008 and 2018 were nearly as few as during the Maunder Minimum. However, sunspots during 2009-2016 were not particularly sparse, in contrast to the Maunder Minimium.)
Section Map: Heat