Archives par mot-clé : Holocene

The 2400-year Bray cycle

by Javier, July 11, 2017 in ClimatEtc.


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.

The Holocene context for Anthropogenic Global warming

by Ed Hoskins, June1, 2015


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.

(i) See also here

(ii) See also here

Three New Papers: Greenland 3-5°C Warmer With 40 Kilometers Less Ice Area 4,000-10,000 Years Ago

by Kenneth Richard, July 11, in ClimateChangeDispatch


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

Global versus Greenland Holocene Temperatures

by Andy May, June 19, 2017 i


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.

A Holocene Temperature Reconstruction Part 4: The global reconstruction

by Andy May, June 9, 2017 in WUWT


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

A Holocene Temperature Reconstruction Part 3: The NH and Arctic

by Andy May, June 8, 2017 in WUWT


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.

 

A Holocene Temperature Reconstruction Part 1: the Antarctic

by Andy May, June1, 2017


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

A paleo-perspective on ocean heat content: Lessons from the Holocene and Common Era

by Yair Rosenthal et al., January 1, 2017


 

Here we review proxy records of intermediate water temperatures from sediment cores in the equatorial Pacific and northeastern Atlantic Oceans, spanning 10,000 years beyond the instrumental record.

These records suggests that intermediate waters were 1.5–2 °C warmer during the Holocene Thermal Maximum than in the last century.

Intermediate water masses cooled by 0.9 °C from the Medieval Climate Anomaly to the Little Ice Age.

 

New Paper: Northern Hemisphere Temperatures Rose 4–5°C Within ‘A Few Decades’ 14,700 Years Ago

By Kenneth Richard , April 2017


According to a new paper, the Bølling Warming event 14,700 years ago raised the surface temperature for the entire Northern Hemisphere by 4 to 5°C within a few decades.  This is a hemispheric warming rate of approximately 2.0°C per decade, which is 40 times faster than the 0.05 °C per decade global warming rate since 1850 (and 1998).