In contrast, two new papers cite evidence that the timing of the lagged CO2 response to temperature changes may have ranged between 1300 and 6500 years in some cases. It would appear that a millennial-scale lagged response to temperature undermines the claim that CO2 concentration changes were a driver of climate in the ancient past.
Because trees may only grow within narrowly-defined temperature ranges and elevations above sea level, perhaps the most reliable means of assessing the air temperatures of past climates is to collect ancient treeline evidence. In a new paper, Kullman (2018) found tree remnants at mountain sites 600 to 700 meters north of where the modern treeline ends, strongly implying Early Holocene air temperatures in northern Sweden were 3-4°C warmer than recent decades.
In Figure 29 of that paper, Hansen claims to show that sea level rise has been accelerating, from 0.6 mm/year from 1900 to 1930, to 1.4 mm/year from 1930 to 1992, and 2.6 mm/year from 1993 to 2015.
The solar activity in the past millennia can only be reconstructed from cosmogenic radionuclide proxy records in terrestrial archives. However, because of the diversity of the proxy archives, it is difficult to build a homogeneous reconstruction. All previous studies were based on individual, sometimes statistically averaged, proxy datasets. Here we aim to provide a new consistent multi- proxy reconstruction of the solar activity over the last 9000 years, using all available long-span datasets of 10Be and 14C in terrestrial archives.
In his seminal 1982 book Climate, History, and the Modern World, the renown climatologist Dr. H.H. Lamb revealed that sea ice in the subarctic and Arctic regions was much less extensive during the Medieval Warm Period (9th-13th centuries) compared to today.
For example, records indicate that there were decadal and centennial-scale periods without any sea ice invading any of Iceland’s coasts. These no-ice periods coincided with atmospheric CO2 concentrations of 275 ppm, which is about 130 ppm less than today’s calculated CO2 values.
GEOMAR researchers find links between sedimentation and methane seeps on the seafloor off the coast of Norway
Large amounts of the greenhouse gas methane are locked up as solid gas hydrates in the continental slopes of ocean margins. Their stability depends on low temperatures and high pressure. However, other factors that influence gas hydrate stability are not as well understood. A German-Norwegian research team has found evidence off the coast of Norway that the amount of sediment deposited on the seafloor can play a crucial role. The study has been published today in the international journal Nature Communications.
1. During the first 2000 years of our 5000-year civilization, most of the time, the annual average temperature was 2ºC higher than now. The temperature in January was 3-5ºC higher than now.
2. From then on, there was a series of temperature fluctuations. The lowest temperatures occurred in AD 1000, 400, 1200, and 1700. The range of fluctuation was 1-2ºC.
3. In every 400-800 period, a smaller cycle lasting 50 to 100 years can be detected with a temperature range of 0.5 -1ºC.
4. During the above cycles, it seems that any coldest period started from the Pacific coast of East Asia. The cold waves then moved westward to Europe and the Atlantic coasts. And at the same time, there were also trends from the North to the South.
Climate change is a reality attested by past records. Concerns about preparing and adapting for climate change are real. However, the idea that we can prevent climate change from happening is dangerous and might be anti-adaptive. Certain energy policies that might have no effect on climate change could make us less able to adapt.
Physics shows that adding carbon dioxide leads to warming under laboratory conditions. It is generally assumed that a doubling of CO2 should produce a direct forcing of 3.7 W/m2 [1], that translates to a warming of 1°C (by differentiating the Stefan-Boltzmann equation) to 1.2°C (by models taking into account latitude and season). But that is a maximum value valid only if total energy outflow is the same as radiative outflow. As there is also conduction, convection, and evaporation, the final warming without feedbacks is probably less. Then we have the problem of feedbacks that we don’t know and cannot properly measure. For some of the feedbacks, like cloud cover we don’t even know the sign of their contribution. And they are huge, a 1% change in albedo has a radiative effect of 3.4 W/m2 [2], almost equivalent to a full doubling of CO2.
by Deming Kong et al., November 30, 2017 in Quaternary International
High-resolution surface temperature records over the last two millennia are crucial to understanding the forcing and response mechanism of Earth’s climate. Here we report a bidecadal-resolution sea surface temperature (SST) record based on long-chain alkenones in a gravity sediment core retrieved from the northern South China Sea. SST values varied between 26.7 and 27.5 °C, with a total variability ∼1 °C over the last 2000 years.
Considering the likelihood of future presentations and discussions, an update of paleoclimatological information was overdue. I was amazed to bump into a full overview of the atmospheric CO2 content of the last 420 million years published much earlier this year. An important milestone in the history of climate on Earth
by Javier, September 15, 2017, in Judith Curry Climate Etc.
The existence of a 1500-year climatic cycle during the Holocene, related to the glacial Dansgaard-Oeschger cycle, is a matter of intense debate. However, by introducing precise timing requirements it can be shown that the 1500-year cycle displayed in Northern Hemisphere glacial records is also observed in Holocene records from all over the world.
The cycle is most prominently displayed in oceanic subsurface water temperatures, Arctic atmospheric circulation, wind deposits, Arctic drift ice, and storminess records.
This modern rate – just 0.17-0.18 of a meter per century –has remained relatively unchanged from the overall 20th century average, and there has been no statistically significant acceleration in the sea level rise rate (just 0.0042 mm/yr-²) since 1900.
Here’s another blow to the global warming alarmist scientists, who have been claiming that the Medieval Warm Period was a local, North Atlantic phenomenon, and did not really exist globally. What follows is a report on yet another paper contradicting this now worn out claim.
The Bray cycle is about 2450 years from beginning to end and the Bray Lows, which are the coldest portion of the cycle, are the most important events.
The world is currently within the Quaternary Ice Age and nearly as cold as it has ever been. The normal average temperature of the world is around 20°C, some 5°C warmer than today. To keep recent warming in perspective, it is important to understand that even if the worse predictions of the IPCC were to occur, we would only be returning to the average temperature of the last 560 million years
Detailed pattern correlation of Earth’s temperature changes during the past 450 kyrs reveals observations about several cyclic climate patterns. The past four glacial cycles are increasing in duration from 89 kyrs to 119 kyrs. Within these glacial cycles, two warm periods occur about 200 kyrs apart and have strikingly similar temperature characteristics.
During the last 450 kyrs, the five major warm onsets with rapidly increasing temperatures are triggered by increases in the eccentricity, obliquity, and precession of Earth’s orbit. The nearly concurrent increase in these three astronomical forces appears a necessary component for a major warm onset. Obliquity is the dominate control for ending these major warm periods and entering a cooling phase.
We present a decadal-centennial scale Holocene climate record based on trace elements contents from a 65 cm stalagmite (“Père Noël”) from Belgian Père Noël cave. Père Noël (PN) stalagmite covers the last 12.7 ka according to U/Th dating. High spatial resolution measurements of trace elements (Sr, Ba, Mg and Al) were done by Laser- Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS). Trace elements profiles were interpreted as environmental and climate changes in the Han-sur-Lesse region.
In our attempt to better understand the nature of our planet’s abrupt climate changes I have already reviewed the glacial-interglacial cycle, and the Dansgaard-Oeschger cycle’s that take place during glacial periods. I now start reviewing the millennial climate cycles that abruptly impact the slowly changing Holocene climate. The most significant and regular one is the ~ 2400-year Bray cycle.
When considering the scale of temperature changes that alarmists anticipate because of Man-made Global Warming and their view of the disastrous effects of additional Man-made Carbon Dioxide emissions in this century, it is useful to look at climate change from a longer term, century by century and even on a millennial perspective.
It’s official. According to a new paper published in the journal Scientific Reports,Greenland has been cooling slightly since 2005.
This trend development may be a harbinger of what may be in store for the coming years. Shifts in North Atlantic temperatures typically lead changes in the Arctic by a few years. And throughout the North Atlantic, rapid cooling has been underway since 2005, plunging below the levels reached in the 1950s
Last week, I posted a global temperature reconstruction based mostly on Marcott, et al. 2013 proxies. The post can be found here. In the comments on the Wattsupwiththat post there was considerable discussion about the difference between my Northern Hemisphere mid-latitude (30°N to 60°N) and the GISP2 Richard Alley central Greenland temperature reconstruction (see here for the reference and data). See the comments by Dr. Don Easterbrook and Joachim Seifert (weltklima) here and here, as well as their earlier comments.
In previous posts (here, here and here), we have shown reconstructions for the Antarctic, Southern Hemisphere mid-latitudes, the tropics, the Northern Hemisphere mid-latitudes, and the Arctic. Here we combine them into a simple global temperature reconstruction. The five regional reconstructions are shown in figure 1. The R code to map the proxy locations, the references and metadata for the proxies, and the global reconstruction spreadsheet can be downloaded here
As we did in the previous two posts, we will examine each proxy and reject any that have an average time step greater than 130 years or if it does not cover at least part of the Little Ice Age (LIA) and the Holocene Climatic Optimum (HCO). We are looking for coverage from 9000 BP to 500 BP or very close to these values. Only simple statistical techniques that are easy to explain will be used.
In the last post (see here) we introduced a new Holocene temperature reconstruction for Antarctica using some of the Marcott, et al. (2013) proxies. In this post, we will present two more reconstructions, one for the Southern Hemisphere mid-latitudes (60°S to 30°S) and another for the tropics (30°S to 30°N)
The Marcott, et al. 2013 worldwide reconstruction has its problems, but many of the proxies used in the reconstruction are quite good and very usable.
The Antarctic reconstruction created here is comparable to previous temperature reconstructions, especially those focusing on eastern Antarctica. It shows two climatic optima, one from 11500 BP to 9000 BP and another from 6000 BP to 3000 BP. In eastern Antarctica, using our proxies, the later optimum is warmer. But, in other areas the earlier optimum is warmer, however, the difference is small
La géologie, une science plus que passionnante … et diverse
