Warming and Dimming: Interactive Impacts on Potential Summer Maize Yield in North China Plain
, Qijin He 1,2, Binxiang Huang 1,2,* and Xuebiao Pan 1,2,*
Round 1
Reviewer 1 Report
Summary:
This study assesses the impacts of climate change associated with climate warming and global dimming/brightening on potential light-temperature productivity (PTP) of summer maize using high-frequency daily observation data collected between 1961 and 2015 in the North China Plain (NCP). Analysis shows that the region has experienced continuous warming patterns during the past 55 years, with 2000-2015 being warmer and dimmer than any previous decades. While warming climate would increase PTP of summer maize, this positive impact would be offset by
Comments:
The study raises a good motivation to conduct this research, and the findings would have important policy implications. Thus, I would encourage the authors to summarize key contributions explicitly in the introduction section.
In the introduction section, it would be useful if the authors could add another paragraph explaining the rationale and validity of the results identified. This would help strengthen the findings from this study.
In the discussion section of results, the study has referenced other studies conducted using datasets from different parts of the world. It would be useful to include point estimates from those studies to compare with those obtained in this study. This would help readers to understand whether the numbers obtained in this study are high or low relative to those identified in other studies.
Finally, in the conclusions section, it would be useful to highlight some policy implications emerging from this study.
Author Response
Point 1: The study raises a good motivation to conduct this research, and the findings would have important policy implications. Thus, I would encourage the authors to summarize key contributions explicitly in the introduction section. In the introduction section, it would be useful if the authors could add another paragraph explaining the rationale and validity of the results identified. This would help strengthen the findings from this study. Response 1: Yes, very right. We added the following contents in the introduction section, “This study focuses on the impacts of temperature and solar radiation on potential light-temperature productivity (PTP) (He et al., 2017). The PTP of summer maize represents the maximum yield under well-watered and stress-free conditions in a given region, which has been widely used to evaluate the spatiotemporal changes of crops under climate change (e.g. Tao et al., 2015; Binder et al., 2008). As PTP was only determined by radiation and temperature, the contribution of the changes in ATT10 and solar radiation on PTP could be separated and calculated by using sensitivity analysis method.” Point 2: In the discussion section of results, the study has referenced other studies conducted using datasets from different parts of the world. It would be useful to include point estimates from those studies to compare with those obtained in this study. This would help readers to understand whether the numbers obtained in this study are high or low relative to those identified in other studies. Response 2: Yes, very right. We added the following contents in the discussion section, “Li et al. (2011) found that maize yield per unit area in the 2000s was almost double the yield in the 1970s, and 11.2% of the increase was resulted from climate change. This study confirmed that climate warming has positive impact on the PTP with an average contribution rate of 4.6% in the past 55 years. Meng et al. (2013) also found a similar result in the Northeast China.” Point 3: Finally, in the conclusions section, it would be useful to highlight some policy implications emerging from this study. Response 3: Yes, we added the sentence in the conclusions section. “The government may promote some agronomic technical measures or new varieties to improve radiation use efficiency, which could greatly increase the farmers’ maize yield.”Reviewer 2 Report
Journal: Sustainability
Manuscript title: Warming and Dimming: Interactive impacts on potential summer maize yield in the North China Plain
Although the paper is nicely written and has prospects, however, in its current state it cannot be accepted for publication and needs some modifications to be done. Please find my comments below:
In the abstract, the number of words is around 270 which is a bit much. Kindly write concisely and try to limit within 250 words.
It’s better to conclude the abstract while mentioning the global application of this study. At present, it seems the findings are only useful for the NCP region.
Your introduction is weak. It fails to identify the problem and demonstrate the reason/importance of this study. The introduction should be written based on addressing the following:
What is global dimming and brightening? How does it affect agriculture and in particular maize productivity? If you are talking about NCP in the introduction it becomes more of a regional study and given that Sustainability is an international journal it is better to write the paper for an international perspective. For example, in Ln 54-57 you have written about the plausible impacts of climate change on maize productivity in NCP region. It is better to focus on global scale studies. Shape the paper in a way that it shows the findings can be of global use and you have used NCP as a case study. Also, there should be a novelty statement in the introduction explicitly showing why this study is of importance.
Where did you collect the maize yield data from and of which cultivar?
Please provide a bigger and high-resolution picture for Figure 1.
Since your paper is on climate change implications, please provide a table with average and standard deviation values of the meteorological variables mentioned in section 2.1.
Ln 97-98: You have mentioned that Bunting (1979) identified a strong relationship among 10⁰C as the threshold and corn growth. But the studies Bunting conducted was in England which has very different climatic conditions compared to NCP and also this relationship is highly sensitive to cultivars. Therefore, a strong regional justification is required for selection of 10⁰C.
Ln 105: Please cite Yadav et al. (2016) along with Allen et al. (1998)
Yadav S, Deb P, Kumar S, Pandey V, Pandey PK. 2016. Trends in major and minor meteorological variables and their influence on reference evapotranspiration for mid-Himalayan region at east Sikkim, India. Journal of Mountain Science, 13(2): 302-315.
Throughout the paper be consistent with the usage of acronyms such as Rs. Some places such as in Ln 113 you have written as normal text (Rs) whereas, in some places such as Eq. 4 they are in italics (Rs). Please be consistent and this applies to all other acronyms used in the paper such as “k” in Eq. 5 and Ln 122 where it is “K” and all other acronyms. This is very serious and makes a reader confused.
Ln 143-146: These sentences are a bit confusing. Did you calculate β for each chunk of 10 years i.e. for 50 years and then what happened to the last 5 years? Also, F-test was done for which sets of dataset as F-test is used to compare statistical models.
Improve the quality of all the Figures. These figures are too small and are of poor quality.
Ln 191: Are these ATT10 values per decade? If so then provide /d after ⁰C.
Ln 277-279: This sentence is contradictory to several other studies such as Wang et al. (2011), Li et al. (2014), Deb et al. (2015), Abera et al. (2018) where they have shown that climate change resulting in increased temperature is expected to reduce the maize production and productivity. Any comment on this?
Li X, Takahashi T, Suzuki N, Kaiser HM. 2014. Impact of climate change on maize production in northeast and southwest China and risk mitigation strategies. Procedia APCBEE. 8:11-20.
Abera K, Crespo O, Seid J, Mequanent F. 2018. Simulating the impact of climate change on maize production in Ethiopia, East Africa. Environmental Systems Research, 7:4.
Wang M, Li Y, Ye W, Bornman J, Yan X. 2011. Effects of climate change on maize production and potential adaptation measures: a case study in Jilin province, China. Climate Research, 46: 223-242.
Deb P, Kiem AS, Babel MS, Chu ST, Chakma B. 2015. Evaluation of climate change impacts and adaptation strategies for maize cultivation in the Himalayan foothills of India. Journal of Water and Climate Change, 6(3): 596-614.
The authors need to discuss the fact that if climate change in terms of increasing the temperature is a boon for maize production then why other studies suggest the productivity is reducing under climate change. Please provide a better justification in the discussion along with citing papers mentioned above.
Author Response
Dear Reviewer,
We have revised the paper as your suggestions, and make a point-to-point response. We really appreciate your valuable advice. Thanks again for your patient.
Yours,
HU QI
Manuscript title: Warming and Dimming: Interactive impacts on potential summer maize yield in the North China Plain
Although the paper is nicely written and has prospects, however, in its current state it cannot be accepted for publication and needs some modifications to be done. Please find my comments below:
Point 1: In the abstract, the number of words is around 270 which is a bit much. Kindly write concisely and try to limit within 250 words.
It’s better to conclude the abstract while mentioning the global application of this study. At present, it seems the findings are only useful for the NCP region.
Response 1: Revised.
Point 2: Your introduction is weak. It fails to identify the problem and demonstrate the reason/importance of this study. The introduction should be written based on addressing the following:
What is global dimming and brightening? How does it affect agriculture and in particular maize productivity? If you are talking about NCP in the introduction it becomes more of a regional study and given that Sustainability is an international journal it is better to write the paper for an international perspective. For example, in Ln 54-57 you have written about the plausible impacts of climate change on maize productivity in NCP region. It is better to focus on global scale studies. Shape the paper in a way that it shows the findings can be of global use and you have used NCP as a case study. Also, there should be a novelty statement in the introduction explicitly showing why this study is of importance.
Response 2: Yes, very right. We rewrite the introduction part as your suggestion.
Point 3: Where did you collect the maize yield data from and of which cultivar?
Response 3: The statistical yield data of summer maize were obtained from National Bureau of Statistics of China (http://www.stats.gov.cn/), as mentioned in the title of Figure 8. The statistical output of each province is a mean value, no specific varieties
Point 4: Please provide a bigger and high-resolution picture for Figure 1.
Response 4: Figure 1 has been reproduced.
Point 5: Since your paper is on climate change implications, please provide a table with average and standard deviation values of the meteorological variables mentioned in section 2.1.
Response 5: Add a table in section 2.1.
Table 1. The average and standard deviation values of the meteorological variables in summer maize growing season in the NCP
Mean temperature (°C) | Maximum temperature (°C) | Minimum temperature (°C) | Relative humidity (%) | Precipitation (mm) | Wind speed (m/s) | Sunshine hours (h) | |
Average value | 23.6 | 28.7 | 19.2 | 75.0 | 469.9 | 2.3 | 831.3 |
Standard deviation | 1.1 | 1.3 | 1.4 | 3.7 | 78.3 | 0.7 | 79.8 |
Point 6: Ln 97-98: You have mentioned that Bunting (1979) identified a strong relationship among 10⁰C as the threshold and corn growth. But the studies Bunting conducted was in England which has very different climatic conditions compared to NCP and also this relationship is highly sensitive to cultivars. Therefore, a strong regional justification is required for selection of 10⁰C.
Response 6: Yes, right. Actually, ATT10 has been wildly used for classification of maize cropping system in the world (almost the only indicator). In the paper, we added the following content to make it clear.:
“Bunting (1979) found a strong relationship between AAT with a given threshold temperature of 10 °C (AAT10) and corn growth, and Bai et al (2008) confirmed similar results in China.”
Point 7: Ln 105: Please cite Yadav et al. (2016) along with Allen et al. (1998)
Yadav S, Deb P, Kumar S, Pandey V, Pandey PK. 2016. Trends in major and minor meteorological variables and their influence on reference evapotranspiration for mid-Himalayan region at east Sikkim, India. Journal of Mountain Science, 13(2): 302-315.
Response 7: Revised.
Point 8: Throughout the paper be consistent with the usage of acronyms such as Rs. Some places such as in Ln 113 you have written as normal text (Rs) whereas, in some places such as Eq. 4 they are in italics (Rs). Please be consistent and this applies to all other acronyms used in the paper such as “k” in Eq. 5 and Ln 122 where it is “K” and all other acronyms. This is very serious and makes a reader confused.
Response 8: Revised. It’s really a very serious point. We write all acronyms in italics in the paper.
Point 9: Ln 143-146: These sentences are a bit confusing. Did you calculate β for each chunk of 10 years i.e. for 50 years and then what happened to the last 5 years? Also, F-test was done for which sets of dataset as F-test is used to compare statistical models.
Response 9: It's not so. In the regression equation formula:
X = k1t + k0, t = 1, 2, 3, ..., n |
where X is climatic variable, k1 is the linear slope, k0 is the y-axis intercept value, t is the number of years.
k1 is first determined by using least-square method, and k0 is then determined by any set of data (X, t).
The climate trend value (β, unit of value per decade) equals to 10 times of k1. So, there is only one β value for a time period (55 years in this paper).
The regression equation, take temperature as an example, is shown in the following figure:
F-test was done for the SSE (Sum of Squares for Error) and SSR (Sum of Squares for regression). SSE and SSR are calculated by:
Where xi is the actual climatic data, Xi is the analog data calculated by the regression equation.
Point 10: Improve the quality of all the Figures. These figures are too small and are of poor quality.
Response 10: Revised. The resolution of all the Figures is 300 dpi.
Point 11: Ln 191: Are these ATT10 values per decade? If so then provide /d after ⁰C.
Response 11: It’s not so. “…the ATT10 in maize growing season in the NCP has increased by about 75.4 oC·d in the recent 55 years with the average trend value of 13.7 oC·d·decade-1” Here, 75.4 oC·d is the total increase amount of ATT10, which is calculated by the trend (13.7 oC·d·decade-1) times years (5.5 decade, i.e., 55 years).
Point 12: Ln 277-279: This sentence is contradictory to several other studies such as Wang et al. (2011), Li et al. (2014), Deb et al. (2015), Abera et al. (2018) where they have shown that climate change resulting in increased temperature is expected to reduce the maize production and productivity. Any comment on this?
Li X, Takahashi T, Suzuki N, Kaiser HM. 2014. Impact of climate change on maize production in northeast and southwest China and risk mitigation strategies. Procedia APCBEE. 8:11-20.
Abera K, Crespo O, Seid J, Mequanent F. 2018. Simulating the impact of climate change on maize production in Ethiopia, East Africa. Environmental Systems Research, 7:4.
Wang M, Li Y, Ye W, Bornman J, Yan X. 2011. Effects of climate change on maize production and potential adaptation measures: a case study in Jilin province, China. Climate Research, 46: 223-242.
Deb P, Kiem AS, Babel MS, Chu ST, Chakma B. 2015. Evaluation of climate change impacts and adaptation strategies for maize cultivation in the Himalayan foothills of India. Journal of Water and Climate Change, 6(3): 596-614.
The authors need to discuss the fact that if climate change in terms of increasing the temperature is a boon for maize production then why other studies suggest the productivity is reducing under climate change. Please provide a better justification in the discussion along with citing papers mentioned above.
Response 12: The four studies are all take the assessment relying on the crop model under current climate and future projections.
The changes for the maize production and productivity in the future are not certain as their reports.
Li et al. (2014) reports that his finding challenges the prevalent view that the climate change has a universally negative effect on Chinese agriculture and implies that a higher flexibility of maize producing timing.
The findings of Abera et al. (2018) and Wang et al. (2011) both show that there are great differences among regions. Abera et al. (2018) find that maize yields will decrease by up to 43 and 24% by the end of the century at Bako and Melkassa stations, respectively, while simulated maize yield in Hawassa show an increase of 51%. Wang et al. (2011) shows that the yield is highly likely to decline in the western and central regions of Jilin but to increase in the east.
As you mentioned that they have shown that climate change resulting in increased temperature is expected to reduce the maize production and productivity. Actually, that’s a certainly result for crop models they used, because increased temperature will accelerate crop growth and shorten growth period, which lead to a reduced grain-filling period and decreased maize production and productivity. We thought about that and took a step forward. In discussion part, we write “Climate warming would have positive effects on improving the grain yield by extending the geographical distribution and providing longer growing season (Olesen et al., 2011; Yang et al., 2011b; Liu et al., 2010). Similar results were also reported in the Northeast China by Liu et al. (2013). It should be noted that, this conclusion is based on the assumption of an invariant maize growing season. However, rising temperatures are expected to accelerate crop growth (Bonfante et al. 2015) and shorten the length of reproductive growth stage (Xiao et al., 2016), and thus reduce the total dry biomass. Therefore, some effective management options, as well as shifting cultivars in longer growing season, have be used to offset the negative impact caused by climate warming.”
Deb et al. (2015) also reports that the projected decline in maize yield could be offset by early planting of seeds, introducing supplementary irrigation and shifting to heattolerant varieties of maize.
So I think these results do not conflict. What we emphasize is that the increased temperature prolongs the growing season and improves potential production, so the maize production and productivitys can be increased by shifting cultivars in longer growing season.
We cited papers mentioned above in the discussion part for the future climate scenarios to make the paper more complete.
Reviewer 3 Report
The article is focused on evaluation the impact of warming and dimming on the potential of summer maize crops in North China Plain. The analysis was based on the data obtained from the China Meteorological Data Sharing Service Network (55 Meteorological Stations) during the 1961 - 2015 survey period (55 years). Especially active accumulated temperature over 10 °C, the solar radiation and potential light-temperature productivity were the investigated parameters. The authors of the paper provide an accurate methodological approach to achieving results from input values (daily mean temperature, maximum temperature, minimum temperature, sunshine hours, wind speed, relative humidity, air pressure and precipitation). To assess the significance of trends, they applied the F-test method and used a non-parametric Mann-Kendall test to determine the breakpoint of time series of temperature and solar radiation. The results showed the conclusions, where North China Plain showed a trend of warming and dimming on a decade scale. A special situation occurred in the mid-1990s when there were abrupt changes in accumulated temperature and solar radiation. The authors described the results in detail based on defined methodologies and came to the overall conclusion, that climate warming and dimming occurred in the North China Plain during the maize growing period, resulting in a reduction in the potential light-temperature productivity. Corn yield also depends on other parameters. I would also suggest adding the parameters of varieties of maize, soil type and so on.
Strengths side:
Ø Research includes an extensive time period.
Ø The number of meteorological stations is enough.
Ø The authors have done a lot of work with the results processing.
Ø The methodology and work results are at the required level.
Weaknesses side:
Ø The quality of some images is low.
Ø Figure 8 would suggest improving.
Ø
Other comments:
143 - How k0 was determined?
Table 2 - Please correct the word - the dedade on the decade.
In the formulas, please correct You the applying or non-applying the dot (times).
Author Response
Point 1: Figure 8 would suggest improving.
Response 1: Figure 8 has been reproduced.
Point 2: 143 - How k0 was determined?
Response 2:
X = k1t + k0, t = 1, 2, 3, ..., n |
where X is climatic variable, k1 is the linear slope, k0 is the y-axis intercept value, t is the number of years.
k1 is first determined by using least-square method, and k0 is then determined by any set of data (X, t).
Point 3: Table 2 - Please correct the word - the dedade on the decade.
Response 3: Corrected.
Point 4: In the formulas, please correct You the applying or non-applying the dot (times).
Response 3: Revised.
Round 2
Reviewer 2 Report
The paper has improved significantly after the revision .
