Inter-decadal climate variability in the Southern Hemisphere: evidence from Tasmanian tree rings over the past three millennia

EXTRACT (SEE PDF FOR FULL ABSTRACT): The characterization of inter-decadal climate variability in the Southern Hemisphere is severely constrained by the shortness of the instrumental climate records. To help relieve this constraint, we have developed and analyzed a reconstruction of warm-season (November-April) temperatures from Tasmanian tree rings that now extends back to 800 BC. A detailed analysis of this reconstruction in the time and frequency domains indicates that much of the inter-decadal variability is principally confined to four frequency bands with mean periods of 31, 57, 77, and 200 years. ... In so doing, we show how a future greenhouse warming signal over Tasmania could be masked by these natural oscillations unless they are taken into account.

Multivariate climate reconstruction for the last 14,000 years in southernmost South America

Comparison between past changes in pollen assemblages and stable isotope ratios (deuterium and carbon) analyzed in the same peat core from Tierra del Fuego at latitude 55°S permitted identification of the relative contribution of precipitation versus temperature responsible for the respective change. Major steps in the sequence of paleoenvironmental changes, such as at 12700, 9000, 5000, and 4000 years ago are apparently related only to increase in precipitation, reflecting the latitudinal location and intensity of the westerly storm tracks. On the other hand, high paleoenvironmental variability, which is characteristic for the late-glacial and the latest Holocene, is related to temperature variability, which affects the relative moisture content. Comparison with other paleoenvironmental records suggests that the late-glacial temperature variability is probably related to variability in the extent of Antarctic sea-ice, which in turn appears to be related to the intensity of Atlantic deep-water circulation. Temperature variability during the latest Holocene, on the other hand, is probably related to the dynamics of the El Niño/Southern Oscillation.

An overview of decadal to century time-scale variability in the climate system

EXTRACT (SEE PDF FOR FULL ABSTRACT): Time scales extracted from high-resolution proxy records and observations indicate that the spectrum of climate variability exhibits significant power in the range of decades to centuries superimposed on a red-noise continuum. The classical view of climate variability is based on the concept that observed fluctuations have their origin in periodic forcings on the same time scale. ... Instead, it is proposed that these fluctuations are linked to interactions within and between the different climate system components.

Determining the role of linear and nonlinear interactions in records of climate change: possible solar influences in annual to century-scale records

Time series analysis methods have traditionally helped in identifying the role of various forcing mechanisms in influencing climate change. A challenge to understanding decadal and century-scale climate change has been that the linkages between climate changes and potential forcing mechanisms such as solar variability are often uncertain. However, most studies have focused on the role of climate forcing and climate response within a strictly linear framework. Nonlinear time series analysis procedures provide the opportunity to analyze the role of climate forcing and climate responses between different time scales of climate change. An example is provided by the possible nonlinear response of paleo-ENSO-scale climate changes as identified from coral records to forcing by the solar cycle at longer time scales.

Radiolarian flux in the Santa Barbara Basin as an index of climate variability

Annual radiolarian flux (1954-1986) extrapolated from varved Santa Barbara Basin sediments was compared to instrumental data to examine the effect of interannual climate variability. Paleo-reconstructions over large geographic areas or 10^3 years and longer typically rely on changes in species composition to signal environment or climate shifts. In the relatively short period studied, climate fluctuations were insufficient to significantly alter the assemblage, but there was considerable variability in the total flux of radiolarians. This variability, greatest on 5- to 25-year time scales, appears to be linked to regional climate variability. Total flux correlates to regional California sea surface temperature and the composite of sea level pressure over the Northern Hemisphere for years of high radiolarian flux resembles positive PNA circulation.

Proceedings of the Eleventh Annual Pacific Climate (PACLIM) Workshop, Asilomar, California - April 19-22, 1994 [appendices]

The appendices include the workshop agenda, a list of poster presentations, and a list of attendees.

Climate forcing by changing solar radiation

By how much does changing radiation from the Sun influence Earth's climate compared with other natural and anthropogenic processes? Answering this question is necessary for making policy regarding anthropogenic global change, which must be detected against natural climate variability. Current knowledge of the amplitudes and time scales of solar radiative output variability available from contemporary solar monitoring and historical reconstructions can help specify climate forcing by changing radiation over multiple time scales.

Effects of interdecadal climate variability on the oceanic ecosystems of the northeast Pacific Ocean [abstract]

EXTRACT (SEE PDF FOR FULL ABSTRACT): It is increasingly apparent that a major reorganization of the Northeast Pacific biota transpired following a climatic "regime shift" in the mid-1970s. In this paper, we characterize the effects of interdecadal climate forcing on the oceanic ecosystems of the northeastern Pacific Ocean.

Terrestrial ecosystem response to interdecadal climate variability in the western United States [abstract]

EXTRACT (SEE PDF FOR FULL ABSTRACT): We argue that the most important climatically-driven terrestrial ecosystem changes are concentrated in annual- to decadal-scale episodic events. These rapid ecosystem responses to climate change are manifested as regionally synchronized disturbance events (eg, floods, fires, and insect outbreaks) and increased drought-caused plant mortality rates.

The terrestrial record of interdecadal climate variability in western North America [abstract]

EXTRACT (SEE PDF FOR FULL ABSTRACT): Western North America is particularly rich in natural records of climate that have potential to reveal features of interdecadal climate variability.

Decadal climate variability over the North Pacific and North America: dynamics and predictability [abstract]

EXTRACT (SEE PDF FOR FULL ABSTRACT): The dynamics and predictability of decadal climate variability over the North Pacific and North America are investigated by analyzing various observational datasets and the output of a state-of-the-art coupled ocean-atmosphere general circulation model, which was integrated for 120 years.

Recent trends in the climate of the tropical Pacific region

EXTRACT (SEE PDF FOR FULL ABSTRACT): Observations of climate variables in the tropical Pacific region are examined for the period 1970-1994. We look at a variety of climate variables, including upper ocean temperatures, surface wind stress, precipitation, and the Southern Oscillation Index (SOI) and find evidence for two distinct decadal-scale warmings in the tropical Pacific ocean-atmosphere climate system during this period.

Analysis of four decades of high elevation climate data

Four decades of instrumented climate records at D1 on Niwot Ridge suggest that high elevation data are an important - and even unique - part of the full climate picture. High elevation data provide information on changing lapse rates as well as model verification for global warming, which is predicted to occur earliest in high latitudes and at high elevations. The D1 records show climatic trends that arguably support global warming, assuming that greater planetary wave amplitude is verification of warming. Lapse rates reflect conditions of air mass stability, atmospheric moisture, and could [sic] cover, which contribute to feedback processes involving temperature, precipitation, and snowpack. The D1 record show a period, 1981-1985, when the lapse rate increased significantly, and this change was not detected by other data.