Kiwi scientists have helped build the most complete database yet on how the planet's climate has changed from 1AD to the present.

The second version of the PAGES2k dataset, just featured in the journal Scientific Data, pools data from a vast array of sources - including records from tree rings, corals, glacier ice, and for the first time, marine and lake sediments - to create a crucial tool to model or reconstruct climates.

An initial summary of global temperature history, developed using the database, confirms a long-term cooling trend until the 19th century, which is then followed by a sharp warming trend - something consistent with the large body of current climate research.

"The fundamental purpose of this compilation is to provide regionally resolved temperature reconstructions that can be used to accurately assess and thus improve Earth system models providing future projections," said co-author Dr Nancy Bertler, of Victoria University.


This would be important for models to be used in the next major report by the UN's Intergovernmental Panel on Climate Change.

"This new database is the most comprehensive and rigorously assessed global temperature reconstruction available to date which includes almost 700 records representing temperature proxies for all continents and oceans."

It focused on the past 2000 years because of the availability of high quality, well dated, well constrained data - availability dropped sharply for earlier time periods, Bertler said.

New Zealand researchers contributed three ice core records, which provided a detailed reconstruction of temperature variability in the Ross Sea region.

This was a particularly sensitive part of Antarctica affecting conditions in New Zealand and globally, through changes in ice sheet mass balance, ocean currents, sea ice and atmospheric CO2 concentration.

Work led by overseas colleagues in collaboration with Kiwi scientists also added three tree ring records from New Zealand to the compilation.

"This is important because global climate models can therefore test how well they capture or represent conditions and changes in New Zealand, which is important to provide meaningful projections for our future."

Bertler said the data was freely available and new groups had already started using it to investigate regional and global temperature trends and patterns, and what was driving them.


She recently co-authored a new Antarctic study that drew on the resource.

"The database is a goldmine for climate scientists and will help to seriously accelerate and fine-tune our efforts in understanding the regional expression of global change and its future trends."