Lincoln Centre for Water and Planetary Health, School of Geography, University of Lincoln, Lincoln, UK.
Cambridge Coastal Research Unit, Department of Geography, University of Cambridge, Cambridge, UK.
Nature. 2018 Sep;561(7722):231-234. doi: 10.1038/s41586-018-0476-5. Epub 2018 Sep 12.
The response of coastal wetlands to sea-level rise during the twenty-first century remains uncertain. Global-scale projections suggest that between 20 and 90 per cent (for low and high sea-level rise scenarios, respectively) of the present-day coastal wetland area will be lost, which will in turn result in the loss of biodiversity and highly valued ecosystem services. These projections do not necessarily take into account all essential geomorphological and socio-economic system feedbacks. Here we present an integrated global modelling approach that considers both the ability of coastal wetlands to build up vertically by sediment accretion, and the accommodation space, namely, the vertical and lateral space available for fine sediments to accumulate and be colonized by wetland vegetation. We use this approach to assess global-scale changes in coastal wetland area in response to global sea-level rise and anthropogenic coastal occupation during the twenty-first century. On the basis of our simulations, we find that, globally, rather than losses, wetland gains of up to 60 per cent of the current area are possible, if more than 37 per cent (our upper estimate for current accommodation space) of coastal wetlands have sufficient accommodation space, and sediment supply remains at present levels. In contrast to previous studies, we project that until 2100, the loss of global coastal wetland area will range between 0 and 30 per cent, assuming no further accommodation space in addition to current levels. Our simulations suggest that the resilience of global wetlands is primarily driven by the availability of accommodation space, which is strongly influenced by the building of anthropogenic infrastructure in the coastal zone and such infrastructure is expected to change over the twenty-first century. Rather than being an inevitable consequence of global sea-level rise, our findings indicate that large-scale loss of coastal wetlands might be avoidable, if sufficient additional accommodation space can be created through careful nature-based adaptation solutions to coastal management.
在 21 世纪，沿海湿地对海平面上升的反应仍然不确定。全球范围的预测表明，目前沿海湿地面积的 20%至 90%（分别对应海平面低和高上升情景）将消失，这将导致生物多样性和高度重视的生态系统服务的丧失。这些预测不一定考虑到所有必要的地貌和社会经济系统反馈。在这里，我们提出了一种综合的全球建模方法，该方法既考虑了沿海湿地通过沉积物堆积而垂直增长的能力，又考虑了适应空间，即细沉积物积累和湿地植被定居的可用垂直和侧向空间。我们使用这种方法来评估全球范围内由于 21 世纪全球海平面上升和人为沿海侵占而导致的沿海湿地面积的变化。根据我们的模拟结果，我们发现，如果超过 37%（我们对当前适应空间的上限估计）的沿海湿地有足够的适应空间，并且沉积物供应保持在目前的水平，那么全球范围内，湿地的增益可能高达当前面积的 60%，而不是损失。与之前的研究相比，我们预测到 2100 年，全球沿海湿地面积的损失将在 0%至 30%之间，假设除了目前的水平之外，没有更多的适应空间。我们的模拟表明，全球湿地的弹性主要由适应空间的可用性驱动，而适应空间的可用性又受到沿海地区人为基础设施建设的强烈影响，预计这种基础设施在 21 世纪会发生变化。如果通过精心设计的基于自然的沿海管理适应解决方案能够创造足够的额外适应空间，那么全球湿地的大规模丧失可能是可以避免的，而不是全球海平面上升的必然结果。
