H2020Индивидуална стипендия2021–2022

SCADI · Snow Core Accumulation from Delta-15N Isotopes

„Хоризонт 2020“ — Действия „Мария Склодовска-Кюри“

Период: 2021-01-01 → 2022-12-31
Финансиране от ЕС: 196 708 €
Участници: 1
Схема: MSCA-IF

Линиите свързват координатора с партньорите.

Накратко на български

Азотните изотопи в снега на Източна Антарктида се анализират, за да се определи колко бързо се натрупва новитеят сняг. Този метод помага за по-точни прогнози за топенето на ледниците и бъдещото повишаване на морското равнище.

Този кратък обзор е генериран от изкуствен интелект

Кратко обяснение, генерирано от езиков модел по текста на CORDIS. Оригиналът е по-долу.

Резултати накратко

Snow Core Accumulation from Delta-15N Isotopes

The East Antarctic ice sheet (EAIS) is the Earth’s largest reserve of glacial ice and could potentially contribute to >1 m of sea level rise by 2100 and >15 m by 2500. Accurate predictions of East Antarctic ice loss are critical for societal adaptation strategies related to future climate change, but models disagree on how the EAIS will respond to future warming. Increased snow accumulation on the EAIS due to warmer air temperatures is expected to partly compensate for greater ice loss to the ocean, but we do not currently know how much compensation is occurring and how it will change with an increasingly warmer planet. More observations of snow accumulation rates on the EAIS could improve modeled projections by providing hard evidence of how the EAIS has and is responding to past and present climate variability. However, the most common methods of determining snow accumulation in Antarctica are logistically intensive and/or fail to work well for the vast regions of the EAIS between the coast and ice sheet dome summits. We sought to develop and apply a new technique for observing accumulation rates based on the nitrogen isotopic ratios of nitrate present in snow and ice. This approach of our project SCADI (Snow Core Accumulation from Delta-15N Isotopes) is based on the phenomenon where nitrate deposited on the Antarctic snow surface has a distinct nitrogen isotopic change after reacting under sunlight. If the snow accumulation rate is lower, the nitrate is exposed to sunlight for a longer time before being buried by later snow and the isotopic change is greater. As a result, analyzing nitrate from many Antarctic sites that cover a wide range of modern accumulation rates would let us mathematically define the relationship between snow accumulation and nitrogen isotopes. Once this relationship is defined, we can calculate a site’s accumulation rate solely by knowing the nitrogen isotopic ratio of the local nitrate. To fully realize this concept, we aimed to (a) create a standardized dataset of nitrate isotopes and accumulation rates for sites spanning the full wet-to-dry range of the EAIS, (b) develop a theoretical model for the relationship between nitrogen isotopes and accumulation rate and then use our standardized dataset to quantify this as an empirical model, and (c) validate this empirical model’s accuracy by applying it to nitrate isotopic data in East Antarctic ice cores. With the conclusion of SCADI, we have successfully achieved these objectives and substantially expanded the understanding of nitrate dynamics in East Antarctica.

Текст от CORDIS, на английски · Данни: CORDIS, © Европейски съюз

Цел на проекта

Future sea level rise threatens infrastructure worth trillions of euros and the livelihoods of millions of people. The magnitude and rapidity of this rise heavily relies on how the mass balance of the East Antarctic Ice Sheet (EAIS) responds to a warming climate, as a net loss of just 1% mass will increase sea level by ~0.7 m. However, any increased ice loss and resulting sea level rise may be partly offset if warming also increases snow accumulation on the EAIS. Currently, our understanding of exactly how EAIS accumulation rates respond to climate change is uncertain as modern records are sparse and the deuterium ratios used as an accumulation proxy in ice cores are affected by several other climate variables. This project aims to fully develop and apply an independent methodology to infer past snow accumulation rates using the fractionation of nitrogen isotopes in nitrate (NO3-). After NO3- is naturally deposited on the Antarctic snow surface, exposure to sunlight promotes photolytic loss of nitrate that favors 14NO3- over 15NO3-. As a result, the 15N/14N ratio (δ15N) of remaining NO3- steadily increases until enough snow accumulates to bury the NO3- below the photic zone and stop the process. Accumulation rate changes can thus extend or reduce the NO3-exposure time and degree of δ15N change. Through a suite of newly collected and archived snow/ice samples that cover a wide range of modern EAIS accumulation rates, the empirical relationship between δ15N and snow accumulation will be quantified and applied to 160 ka of data from the Vostok and EPICA Dome C ice cores. These new δ15N analyses will independently estimate how snow accumulation at the sites responded to the dramatic global climate changes of the past two glacial cycles, including two periods of rapid deglacial warming. In turn, this will produce a clearer understanding of Antarctic climate dynamics and mass balance responses during abrupt climate change and help reduce sea level projection uncertainty.

Оригинален текст от CORDIS (на английски).

Участници

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